[amelia] Trouble with Amelia 1.7.1

Dear Amelia mailing list, I have some code that runs in Amelia 1.6.1 (with R 2.15.0) without any problems. When I run that same code in Amelia 1.7.1 (with R 3.0.0), a few imputations might finish without any error messages, but many finish with the message "The resulting variance matrix was not invertible. Please check your data for highly collinear variables". I understand that this suggests that there may be a problem with the data, but I don't understand why there would be a problem in version 1.7.1 but not in 1.6.1. Also, when I'm using Amelia 1.7.1 in R 3.0.0, R will sometimes crash during the imputation process. I'm running R in emacs in Windows, and I'll sometimes get a pop-up window saying "R for Windows terminal front-end has stopped working", with the following message appearing in emacs: "error: chol(): failed to converge This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. terminate called after throwing an instance of 'std::runtime_error' what(): Process R exited abnormally with code 3 at Fri Apr 05 15:04:58 2013" Amelia 1.7.1 worked without any problems when I tried it on some small made-up data, but not on my real data. I understand that it's almost impossible to diagnose problems without a reproducible example, but I was wondering whether others have had similar problems. Thanks for any comments you can give. Mark Seeto