Imagebutton does not postback after successful validation

[Vamsi]

I have a strange problem on only one server( the works fine on all
other servers).
I have an imagebutton in an aspx page that contains validation
controls. Validation works fine, but once the validation is
successful, the page does'nt post back.
There is some problem with client side javascript that asp.net page
automatically generates.
Imagebutton works fine on pages that have no validation.
We have this problem only on one server and same code works fine on 5
other different servers.
Please help find the problem and solve it!
Thanks,
Vamsi