
Thanks
Error:
System.InvalidOperationException: Telerik.Web.UI.RadWindow with ID='g_78be1aeb_3a1d_4490_9f07_c51834a37899_BindingWindow' was unable to find an embedded skin with the name 'Windows7'. Please, make sure that the skin name is spelled correctly and that you have added a reference to the Telerik.Web.UI.Skins.dll assembly in your project. If you want to use a custom skin, set EnableEmbeddedSkins=false.
at Telerik.Web.SkinRegistrar.GetEmbeddedSkinAttributes(ISkinnableControl control, Type controlType, Boolean designTime)
at Telerik.Web.SkinRegistrar.RegisterCssReferences(ISkinnableControl control)
at Telerik.Web.UI.RadWindow.ControlPreRender()
at System.Web.UI.Control.PreRenderRecursiveInternal()
at System.Web.UI.Control.PreRenderRecursiveInternal()
at System.Web.UI.Control.PreRenderRecursiveInternal()
at System.Web.UI.Control.PreRenderRecursiveInternal()
at System.Web.UI.Control.PreRenderRecursiveInternal()
at System.Web.UI.Control.PreRenderRecursiveInternal()
at System.Web.UI.Control.PreRenderRecursiveInternal()
at System.Web.UI.Control.PreRenderRecursiveInternal()
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
8 Answers, 1 is accepted
This error is caused when the Telerik.Web.Skins.dll assembly cannot be found in the project (additional information in also available in this help article). You can verify that after restart the correct version of the assembly is still in the same place and you have the correct reference in the project.
Generally server reboot should not remove assemblies from the system. We also recommend to keep the assemblies in the GAC and reference them from there.
Regards,
Marin
Telerik
See What's Next in App Development. Register for TelerikNEXT.

This is not a custom project but the SharePoint Web Parts that come with the software. I have no way to check references with this.
Also, I have found that if I go through SharePoint Admin and retract radcontrolssp.wsp and redeploy it, that the error will go away.
One other item, this is a 3 server system (Web, application and SQL).

We replied to your support ticket on the same issue with further suggestions to check IIS setup and web.config settings prior and after the issue happens to see if there are any differences in the two cases.
In order to avoid duplicate posts here we can continue the communication in the other support ticket.
Kind Regards,
Marin
Telerik
See What's Next in App Development. Register for TelerikNEXT.

We are seeing the same issue in our SharePoint environment. Please help.
System.InvalidOperationException:
Telerik.Web.UI.RadWindow with
ID='g_14fb7cf7_0214_4921_a821_77c808af91e0_BindingWindow' was unable to find an
embedded skin with the name 'Windows7'. Please, make sure that the skin name is
spelled correctly and that you have added a reference to the
Telerik.Web.UI.Skins.dll assembly in your project. If you want to use a custom
skin, set EnableEmbeddedSkins=false.
at
Telerik.Web.SkinRegistrar.GetEmbeddedSkinAttributes(ISkinnableControl control,
Type controlType, Boolean designTime)
at
Telerik.Web.SkinRegistrar.RegisterCssReferences(ISkinnableControl
control)
at
Telerik.Web.UI.RadWindow.ControlPreRender()
at
System.Web.UI.Control.PreRenderRecursiveInternal()
at
System.Web.UI.Control.PreRenderRecursiveInternal()
at
System.Web.UI.Control.PreRenderRecursiveInternal()
at
System.Web.UI.Control.PreRenderRecursiveInternal()
at
System.Web.UI.Control.PreRenderRecursiveInternal()
at
System.Web.UI.Control.PreRenderRecursiveInternal()
at System.Web.UI.Control.PreRenderRecursiveInternal()
at
System.Web.UI.Control.PreRenderRecursiveInternal()
at
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint,
Boolean includeStagesAfterAsyncPoint)
The recommendations are the same as in the previous posts in the this thread. Such error can occur if the Telerik.Web.UI.Skins assembly is missing from the project references or if it is a different version than the main Telerik.Web.UI.dll assembly.
You can check the project references, verify that all Telerik assemblies are successfully deployed in GAC and that all are the same version, and finally check the web.config file to make sure that all the Telerik related assemblies are defined in the <SafeControls> section in the web.config file with their correct version.
This should resolve the problem.
Kind Regards,
Marin
Telerik
See What's Next in App Development. Register for TelerikNEXT.

I would suggest you to open a separate support ticket for the current installation issue you are facing, Thus we will be able to better track the case and based on the provided information to provide proper solution for your issue.
Regards,
Maria Ilieva
Telerik