All my apps from the AppStore are crashing, They load the Default.png then go straight back to the spingboard.

Apps installed via Cydia are working fine.

Any ideas?

Also i have tried rebooting it several times to no avail

It's happening to me as well.. I just remove and reinstall the app and got it to work

Yeah thats what ive done, bit of a pain but it works

Most of the issues I have had have been after I installed apps via the phone. If I installed the same apps via iTunes all seemed smoother. We know 2.0 is buggy but so is 7.7. I can't wait for some usable updates. Being an early adopter with Apple can be a frustrating experience.