Hello, I've had FS9 on my computer since it was released and never had a problem,other than the usual performance issues when it first came out. For about the last month I've been getting regular ctd's to the point of making this software unusable. Sometimes it's a soft crash with an error message and other time it's a hard crash resulting in a reboot. When I do get an error message, the reason usually varies. Sometimes it's sim1.dll or d3d9.dll or fsuipc.dll. I don't think it's hardware related only because I can run FSX without a crash. I have uninstalled, reinstalled, deleted the entire directory. I am at a loss to explain why this is happening. Any help would be appreciated.P4 3.2 GHZBFG Geforce 7600 gsoc 512MB2 GB PC 3200 DDR400

Several simmers have received similar crashes with those dll's and there is no magic bullet to fix each crash. It depends on individual system configurations but IMHO the video card drivers are most likely the culprit. Deleting the FS9.cfg and letting the sim rebuild it may fix it too or checking your scenery.cfg for corruption (area/layers do not match numerically, not in numerical sequence, etc.). I would simply suggest you do a search on AVSIM forums using each .dll as a keyword. You can also do a Google search and you'll come up with potential solutions from a variety of fltsim forums. Hope this helps.Best regards,Jim

Jim, Thanks for the reply. I wish I had a dollar for every time I've uninstalled and reinstalled video drivers in the last week. Every time a new error message would show up,I would Google the DLL. Finally, one came up that indicated a possible memory problem. I ran Memtest overnight and sure enough I got an error message. After isolating the bad stick and removing it, FS9 runs like a charm. It's great to be flying again.