I need help

1. I inadvertantly deleted from my XP machine my .pst files.
2. I have had them recovered on DVD
3. I have tried to import them in Vista's Outlook (not express)
4. Get error message that it is not a PST File (but it has the pst file
extension)
5. The Dell tech says it must be corrupt.

Query - Is the file possible corrupt and if so how do I fix it?

If this is a Microsoft system problem - how do solve it
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Thanks for your input