Can you run drwtsn32.exe from start->run, and check the Crash Dump setting? Check the time stamp on that file - does it match a recent crash in Explorer.exe? If so, upload that file to your SkyDrive and provide a link. It may hold some details about why Explorer.exe is crashing.
Often, instabilities in Windows Explorer are attributable to faulty shell extensions and addons.
Consider using Sysinternals Autoruns or ShellExView. Disable non-Microsoft shell extensions and add-ons, and check the behavior. If it is gone, re-enable the disabled extensions/add-ons, one at a time, and see if you can identify which may be responsible.
Try a clean boot, or boot into safe mode. Does the behavior persist?