"The file 'ProgramNameHere' cannot be opened. Either it is not signed with a trusted certificate or one of its components cannot be found. If the problem persists, try reinstalling or restoring the file"

I installed windows mobile 6.1 yesterday and when i went to run some programs i get the message above. The install of 6.1 went smooth but it did act like it failed at the end and told me to reboot the phone and restart. when i did it said it was successful.

The programs i get this message on are all third party apps, mostly games, that worked in 6.0. Some are even programs that people reported on this forum as working in the upgrade such as pocket nester, pac man, etc. Some even run once and fail after a soft reset.

What can i do?

My phone isnt "unlocked" and to be honest i am not entirely sure what that means. I am not above tweaking some stuff but i would like to avoid a custom ROM file just because i am not up on all the advanced phone tweaking.

Thanks in advance!

See the following link to modify the certificate settings (ie, app unlock) -
How to app unlock your HTC S621 Windows Mobile Smartphone - Simple Help