Can't share network with firewall on, can't reset firewall to default

I suddenly noticed my desktop wasn't on the network any more. On inspection, network discovery and file sharing was disabled. I tried to enable it, but it would not. I found out if I turned off the firewall it worked fine. I tried to reset the firewall to default, but I get "Could not restore the default policy: error 3".

How can I reset the firewall to default so I can turn on network discovery and file sharing?

Edit: I forgot to say, I have MSE on and it has not found or alerted me to any malware.. Plus, I have scanned with Malwarebytes and Kaspersky (even pulling the hard drive and scanning from another machine) and they have found nothing..

bump..

Still can't figure this out..

Often times the Windows firewall is the problem although it's likely that Kaspersky is at fault.

How to Repair Windows Firewall Files | eHow.com

The problem is, when I open a cmd prompt and type "netsh advfirewall reset", I get the error:
An unrecoverable Windows Firewall error (0x3) occurred.

How can I get past that?

I have Microsoft Security Essentials that runs all the time, and Malwarebytes (free) that scans when run it.. I installed Kaspersky just to scan, but have already uninstalled it..

The problem happened before I used Kaspersky, I just installed and ran it to see if it found anything (which it did not)..

I'm about ready to start a new administrator account and just transfer everything over.. Sooooo aggravating!!

Fixed the problem!
I read another post here, and the solution worked for me:
- export firewall settings from a known working w7 computer
- import the firewall settings onto the non-working w7 computer

My system now works!