A valid installation of Pro Tools could not be found

[Swivelable]

I know this problem has ben discussed before, but I can't find it in DUC or the FAQ & Troubleshooting Guide.
PT 7.4 runs fine on my iMac 2.8Ghz OS 10.4.10.
But I cannot upgrade, and the Tech Support Utility comes up with the same error.

Why would my once valid installation become unrecognizable as such?
And if it's not recognized as valid, why does it function as valid?

Is there anything short of a total reinstall that will fix this? (which for me would mean installing 7.3 to use my upgrade for 7.4)
Is it even necessary to fix if I don't mind mising the mid level upgrades?

Thanks for any input

[Phil Ogden]

The usual reason for this error is that PT has been moved from it's default install location. Move it back and you should be good to go.

http://www.myspace.com/philogg

[Swivelable]

I love it!

I amended my PT folder with "7.4" so I don't have to dig too deep to keep up with each app's version.
Deleting those 3 digits made my PT valid again. Much simpler than reinstalling!

Muchly appreciated Phil