Tallboy, I've encountered that problem a couple of times and a System Restore was all it took to fix it. If you're not familiar with it then here's how. Pick a date when the computer was running fine but don't go further back than you need to.
Many thanks for the quick replies northumbria61 & Secret-Squirrel. First I tried Method 3 on the Microsoft Support Page - using an MS FixIt routine. This didn't work, so I went to method 1 - careful manual modification of the registry. Fortunately this did work, so my wife can now use her PC again.
Thanks again northumbria61 - it would have taken me ages to locate those pages in Microsot's 'den' of information!
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