I'm assuming because of the F8 message you're running some form of Windows. I'd assume Windows XP. Are you getting any additional message besides the memory code you listed below a line with underscores such as: SYSTEM_THREAD_EXCEPTION_NOT_HANDLED ?
Based off the description of the error it could potentially be any number of things. If I was a betting man I'd first think memory issue. Additional details about checking for bad memory on below link. I'd suggest try running the memtest86 program (link found in below document).
http://www.computerhope.com/issues/ch000708.htmIf memory checks out my next assumption would be driver related issue because this happens on ejection of disc drive. Try updating the drivers for it.
Also have you added any new hardware recently?