Sims 3 crashes after 15 minutes

MiaCezanne  Does the game crash at the same sim-time of day, within a few minutes?  It's possible something is happening at that time and triggering the crashing.

If that's not the case, try playing a different household within the same save.  You don't need to save your progress; this is just for testing.  The idea is, if there's something wrong in the world independent of your main sims, it should happen in the new household too; if the issue has to do with your main household, playing as other sims may help.

While testing, please delete the five cache files in the Sims 3 user folder every time you quit the game or it crashes.  For reference, they are:

• CASPartCache.package
• compositorCache.package
• scriptCache.package
• simCompositorCache.package
• socialCache.package

After each crash, please also empty out the CurrentGame folder, which should always be empty when you don't actually have a save loaded.

Finally, you'll see some xcpt files in the user folder as well.  Delete them all, both the .txt and .mdmp files, and after the next crash, look for new ones.  If you find them, open the .txt file and list the memory stats, starting with total physical memory and ending with free virtual memory.  That section looks like this:

Total physical memory: 12178 Mb
Available physical memory: 3679 Mb
Total page file memory: 11778 Mb
Available page file memory: 4119 Mb
Total virtual memory: 4095 Mb
Free virtual memory: 3069 Mb