Error activating ICS on vista home basic. Error: 0x800702FD

I have an internet connection through a portable modem, and an iPhone connected to the PC using WiFi. I am trying to share my Internet connection to the iPhone via WiFi.

When I successfully created the WiFi network, it gave me an option to share my internet connection. When I clicked it, it resulted in an error "Windows could not set up Internet Connection Sharing (ICS)".

Then, I opened the explorer window showing all the network connections and tried to manually share the internet connection. Following are the steps I followed:

1. selected the network to be shared
2. right click, open properties
3. open 'share' tab
4. check 'Allow other network users to connect through this computer's Internet connection' check box
5. selected the WiFi Network from the drop down list, and click 'OK'

It resulted in an error: Error: 0x800702FD. An operation is blocked waiting for an op-lock.

Firewall is disabled. Have AVG free antivirus installed. DHCP service is running.

Please help.

Solved after some R&D.

Updated AVG Free, scanned for viruses and removed. Then the error turned into cannot enable shared access error 0x80004005 unspecified error Enabled Firewall and everything is working fine now.