Single Page Checkout Having to click twice

Hi,  has anybody run into this with the single page checkout in v1.5

Sometime you have to click twice on the buttons to get to the next step.  Ive also noticed that sometimes you end up back at the shipping address.

This happens with both guest and registered users and in both IE and firefox

Thanks
-Keith

While testing in IE,  I was getting a script error on the page which was system.extended.ui is null so after looking that up it suggested setting CombineScripts="false" in the toolkitscriptmanager, which I did and it fixed the issue.  It’s the toolkitscriptmanger in Modules/CheckoutOnePage.ascx  Here are some observations

1)  Only happens when the site is pre-compiled
2)  I can reproduce setting up a virtual directory for my pre-compiled site in local IIS
3)  Doesn’t Happen in Visual Studio.
4)  On all the button clicks  validation when nop checks that the page is valid,  both on local IIS and my remote server the first and second click both return Page.IsValid=true so the validation is working.

Of course not combining the scripts will suffer a performance hit on the website. So ill look further to see if there are any other ways around it.

Thanks
-Keith