Thanks for the advice but my first step was to check the Manual and I couldn't find error codes listed after going through all the pages. My problem is that intermittently the system will not boot past the Windows startup or if it does get to the desktop, nothing works, it's locked up. Computer worked for two years and now it boots about 1/3 of the time. Uninstalled all recent updates and reinstalled them...nothing improved. When system stalls, I get a code RR.