...hmmm, i thought i'd just abandon avg and tried to install avast. that seems to be coming up with similar problems. on trying to install avast i got the following error
the path ' C:\documents and settings\all users\application data\MFAData\pack\vc_red.msi' cannont be found. verify that you have acces to this location and try again, or try to find the installation package 'vc_red.msi' in a folder from which you can install the product microsoft visual C++ 2008 redistributalbe - x86 9.0.30729.4148
I've check and microsoft visual C++ 2008 redistributalbe - x86 9.0.30729.4148 seems to already be installed