We recently released a VS2010 sp1 QFE KB2650605 to solve a VB editor debugging problem. During VB web form debugging, VB web form may become un-editable if there are server tags inside. If you develop and debug VB web forms, you might be interested to download this QFE.
Update for another download place due to broken link in connect Url: http://blogs.msdn.com/cfs-file.ashx/__key/communityserver-blogs-components-weblogfiles/00-00-00-63-56/3146.VS10SP1_2D00_KB2650605_2D00_x86.exe
Web Platforms and Tools Team