SEM (CFA) in R leads to error - not enough memory? -

i trying conduct confirmatory factor analysis (cfa) in r. keep getting error:

warning message: in eval(expr, envir, enclos) : not compute qr decomposition of hessian. optimization did not converge.

i execute following code:

library(sem) cov.matrix <- cov(na.omit(factor.data))  cfa.model1 <- specifymodel() expert_power -> q9_c, expert1 expert_power -> q9_s, expert2 expert_power -> q9_z, expert3 expert_power -> q9_al, expert4 referent_power -> q9_e, referent1 referent_power -> q9_o, referent2 referent_power -> q9_aa, referent3 referent_power -> q9_ai, referent4 informational_power -> q9_d, informational1 informational_power -> q9_q, informational2 informational_power -> q9_x, informational3 informational_power -> q9_ap, informational4 legitimate_power_of_dependence -> q9_i, ldependence1 legitimate_power_of_dependence -> q9_p, ldependence2 legitimate_power_of_dependence -> q9_y, ldependence3 legitimate_power_of_dependence -> q9_an, ldependence4 personal_reward_power -> q9_h, preward1 personal_reward_power -> q9_n, preward2 personal_reward_power -> q9_ac, preward3 personal_reward_power -> q9_ag, preward4 legitimate_power_of_reciprocity -> q9_g, lreciprocity1 legitimate_power_of_reciprocity -> q9_l, lreciprocity2 legitimate_power_of_reciprocity -> q9_af, lreciprocity3 legitimate_power_of_reciprocity -> q9_aq, lreciprocity4 impersonal_coercive_power -> q9_f, icoercive1 impersonal_coercive_power -> q9_m, icoercive2 impersonal_coercive_power -> q9_ae, icoercive3 impersonal_coercive_power -> q9_am, icoercive4 legitimate_power_of_equity -> q9_k, lequity1 legitimate_power_of_equity -> q9_u, lequity2 legitimate_power_of_equity -> q9_ad, lequity3 legitimate_power_of_equity -> q9_aj, lequity4 impersonal_reward_power -> q9_a, ireward1 impersonal_reward_power -> q9_v, ireward2 impersonal_reward_power -> q9_ak, ireward3 impersonal_reward_power -> q9_ao, ireward4 personal_coercive_power -> q9_j, pcoercive1 personal_coercive_power -> q9_r, pcoercive2 personal_coercive_power -> q9_w, pcoercive3 personal_coercive_power -> q9_ar, pcoercive4 legitimate_power_of_position -> q9_b, lposition1 legitimate_power_of_position -> q9_t, lposition2 legitimate_power_of_position -> q9_ab, lposition3 legitimate_power_of_position -> q9_ah, lposition4 expert_power <-> expert_power, na, 1 referent_power <-> referent_power, na, 1 informational_power <-> informational_power, na, 1 legitimate_power_of_dependence <-> legitimate_power_of_dependence, na, 1 personal_reward_power <-> personal_reward_power, na, 1 legitimate_power_of_reciprocity <-> legitimate_power_of_reciprocity, na, 1 impersonal_coercive_power <-> impersonal_coercive_power, na, 1 legitimate_power_of_equity <-> legitimate_power_of_equity, na, 1 impersonal_reward_power <-> impersonal_reward_power, na, 1 personal_coercive_power <-> personal_coercive_power, na, 1 legitimate_power_of_position <-> legitimate_power_of_position, na, 1 q9_c <-> q9_c, error1 q9_s <-> q9_s, error2 q9_z <-> q9_z, error3 q9_al <-> q9_al, error4 q9_e <-> q9_e, error5 q9_o <-> q9_o, error6 q9_aa <-> q9_aa, error7 q9_ai <-> q9_ai, error8 q9_d <-> q9_d, error8 q9_q <-> q9_q, error10 q9_x <-> q9_x, error11 q9_ap <-> q9_ap, error12 q9_i <-> q9_i, error13 q9_p <-> q9_p, error14 q9_y <-> q9_y, error15 q9_an <-> q9_an, error16 q9_h <-> q9_h, error17 q9_n <-> q9_n, error18 q9_ac <-> q9_ac, error19 q9_ag <-> q9_ag, error20 q9_g <-> q9_g, error21 q9_l <-> q9_l, error22 q9_af <-> q9_af, error23 q9_aq <-> q9_aq, error24 q9_f <-> q9_f, error25 q9_m <-> q9_m, error26 q9_ae <-> q9_ae, error27 q9_am <-> q9_am, error28 q9_k <-> q9_k, error29 q9_u <-> q9_u, error30 q9_ad <-> q9_ad, error31 q9_aj <-> q9_aj, error32 q9_a <-> q9_a, error33 q9_v <-> q9_v, error34 q9_ak <-> q9_ak, error35 q9_ao <-> q9_ao, error36 q9_j <-> q9_j, error37 q9_r <-> q9_r, error38 q9_w <-> q9_w, error39 q9_ar <-> q9_ar, error40 q9_b <-> q9_b, error41 q9_t <-> q9_t, error42 q9_ab <-> q9_ab, error43 q9_ah <-> q9_ah, error44 expert_power <-> referent_power, cov1 expert_power <-> informational_power, cov2 expert_power <-> legitimate_power_of_dependence, cov3 expert_power <-> personal_reward_power, cov4 expert_power <-> legitimate_power_of_reciprocity, cov5 expert_power <-> impersonal_coercive_power, cov6 expert_power <-> legitimate_power_of_equity, cov7 expert_power <-> impersonal_reward_power, cov8 expert_power <-> personal_coercive_power, cov9 expert_power <-> legitimate_power_of_position, cov10 referent_power <-> informational_power, cov11 referent_power <-> legitimate_power_of_dependence, cov12 referent_power <-> personal_reward_power, cov13 referent_power <-> legitimate_power_of_reciprocity, cov14 referent_power <-> impersonal_coercive_power, cov15 referent_power <-> legitimate_power_of_equity, cov16 referent_power <-> impersonal_reward_power, cov17 referent_power <-> personal_coercive_power, cov18 referent_power <-> legitimate_power_of_position, cov19 informational_power <-> legitimate_power_of_dependence, cov20 informational_power <-> personal_reward_power, cov21 informational_power <-> legitimate_power_of_reciprocity, cov22 informational_power <-> impersonal_coercive_power, cov23 informational_power <-> legitimate_power_of_equity, cov24 informational_power <-> impersonal_reward_power, cov25 informational_power <-> personal_coercive_power, cov26 informational_power <-> legitimate_power_of_position, cov27 legitimate_power_of_dependence <-> personal_reward_power, cov28 legitimate_power_of_dependence <-> legitimate_power_of_reciprocity, cov29 legitimate_power_of_dependence <-> impersonal_coercive_power, cov30 legitimate_power_of_dependence <-> legitimate_power_of_equity, cov31 legitimate_power_of_dependence <-> impersonal_reward_power, cov32 legitimate_power_of_dependence <-> personal_coercive_power, cov33 legitimate_power_of_dependence <-> legitimate_power_of_position, cov34 personal_reward_power <-> legitimate_power_of_reciprocity, cov35 personal_reward_power <-> impersonal_coercive_power, cov36 personal_reward_power <-> legitimate_power_of_equity, cov37 personal_reward_power <-> impersonal_reward_power, cov38 personal_reward_power <-> personal_coercive_power, cov39 personal_reward_power <-> legitimate_power_of_position, cov40 legitimate_power_of_reciprocity <-> impersonal_coercive_power, cov41 legitimate_power_of_reciprocity <-> legitimate_power_of_equity, cov42 legitimate_power_of_reciprocity <-> impersonal_reward_power, cov43 legitimate_power_of_reciprocity <-> personal_coercive_power, cov44 legitimate_power_of_reciprocity <-> legitimate_power_of_position, cov45 impersonal_coercive_power <-> legitimate_power_of_equity, cov46 impersonal_coercive_power <-> impersonal_reward_power, cov47 impersonal_coercive_power <-> personal_coercive_power, cov48 impersonal_coercive_power <-> legitimate_power_of_position, cov49 legitimate_power_of_equity <-> impersonal_reward_power, cov50 legitimate_power_of_equity <-> personal_coercive_power, cov51 legitimate_power_of_equity <-> legitimate_power_of_position, cov52 impersonal_reward_power <-> personal_coercive_power, cov53 impersonal_reward_power <-> legitimate_power_of_position, cov54 personal_coercive_power <-> legitimate_power_of_position, cov55   cfa1 <- sem(cfa.model1, cov.matrix, nrow(factor.data)) summary(cfa1,fit.indices=c("rmsea", "nnfi", "cfi")) 

when consider less latent variables in model calculated without problems. when remove last 55 lines of code in specifymodel() command, calculation executed.

since observed relative long duration calculation, , high usage of memory whilst doing so, have suspicion r can't execute calculation due little system memory (2gb). is possible or there other causes problem haven't noticed?