Fatal Exception…VxD MCSCAN32(01)

I have a Dell OptiPlex with 233 Mhz PII running Win95B. I just upgraded my McAfee virus scan engine to 4.5 and downloadwd the latest .dat files. Since then, I’ve been getting the following blue screen and message during bootup-(Fatal Exception OE has occured at 0028:C4DC58AF in VxD MCSCAN32(01) + 000278A3. press any key to continue.) I disabled the virus scan and re booted and the same thing happens. I tried to remove the entire McAfee program but it won’t let me, claiming that dScanDef.mmf andSync_map.mmf are in use by another application. I closed all programs except explorer and tried again with the same results.