Thanks All for your replies -- had to get computer back into commission...so reloaded from Dell recovery.
Vostro 400 is church computer.  I run SpyHunter on it as well as McAfee. Since it is used by many people it is difficult to determine when the Stop errors started; however everyone uses their own usb flash disk to save files, etc. The system is clean for Spyware and McAfee is up to date. The BSOD only happens AFTER the system has written to the flash disk and now the CD as well.  I was completing a back up with Nero Back-it-Up and when the system ejected the first disk, I got the BSOD with a mfehidk.sys error which mapped back to McAfee. McAfee agents uninstalled and reinstalled the program. Every other time, there is no error accompanying the BSOD.  It will reboot into Windows but NOT safe mode -- again the BSOD. System is out of warranty --- and I'm out of ideas...help!!! Julie
Vostro 400 - BSOD after writing to Flash Disk