Hello!
Try to run SEP support tool, located here:
http://www.symantec.com/business/support/index?page=content&id=TECH105414
If this not give a good solution use cleanwipe which tool to remove SEP and reintall is.
You can find the cleanwipe here:
<edit> Link removed by Admin
Actually the correct way to get clenwipe to contact the support, but my way is faster :D
By the way ther is a KB article how to remove sep manulally:
http://www.symantec.com/business/support/index?page=content&id=TECH102261&locale=en_US
If you need more help don't hesitate to come back :)