It sounds like your Epic and/or software needs a checkup. Try downloading the latest software at .....

http://www.melabs.com/downloads/E243BET3.ZIP

Also make sure your powersupply is "juicy" enough, atleast 16V during programming without dips. If you're unsure try using two 9V batteries. "Modern" pics is more demanding regarding the programmingvoltage.

Finally(if you're really desperate) you could check the two resistors that connects RB6&7 to Vcc, you can lower them to 1k(if not done already).

There are lots of troubleshooting info about the Epic here....

http://www.melabs.com/products/epic.htm

Good luck
/Ingvar