CS2001 error after Windows 2003 R2 update

This week I succesfully updated a Microsoft CRM 3.0 / Windows 2003 server to Windows 2003 R2. After the R2 update I received an error when starting Microsoft CRM:

Unable to generate a temporary class (result=1). error CS2001: Source file 'E:\WINDOWS\TEMP\ksgczw3q.0.cs' could not be found error CS2008: No inputs specified

This problem can be fixed by giving the NETWORK SERVICE read en write access to the WINDOWS\TEMP folder.