Do you by any chance have Daemon Tools Installed? I've experinced the same
behavior, and it turned out that it was some sort of conflict with SPTD that
Daemon Tools uses.
http://www.duplexsecure.com/downloads
I even got BSODs every now and then. So I uninstalled Daemon Tolls and made
sure that SPTD was uninstalled 100% and no files of SPTD remained.
I haven't had any freezes after that.
I now use Virtual CD which haven't caused me any trouble yet:
http://www.virtualcd-online.com