do you use xp?
error reporting will, if switched on, offer to send a report to microsoft if a program has a serious error.
can you give us the exact error displayed please?
in the meantime try click here
also click 'start/control panel/system/advanced/start up and recovery/settings' untick 'automatically restart' now when you get a critical error you will see an error screen displayed. note down this error and look it up on the knowledgebase or post it here.
also try 'start/control panel/administrative tools/event viewer' click the 'system' and 'application' tabs and look for errors logged with a red x. click them for more info.