change to asp.net 4.0 causes all disabled buttons to lose their theme

We have a problem on a new server where disabling a themed button loses its theme. This happens consistently on all buttons now.

We just switched to a new iis server 7.5 using asp.net framework 4.0

Before, the buttons through out the website have a nice style/theme. These are not set inside each button and there are no classes set specifically for buttons I dont think but I believe inherit the theme from I believe the web.config in either:

 <appSettings>
    <add key="Telerik.Skin" value="WebBlue" />
...

OR it is set in our custom theme
<system.web>
    <pages styleSheetTheme="Seniors">

All the buttons did display a nice light blue gradient, and when disabled they go a few shades lighter blue

For some reason now in .net framework 4.0 all disabled buttons seem to lose their theme and become the default g ...