Excerpt from Alon’s blog:
Download the patched version: termsrv_sp3_patch.rar
0. Go to C:\Windows\system32\dllcache and rename the termsrv.dll to termsrv.dll.bak
1. Go to \Windows\System32 folder and rename termsrv.dll to termsrv.dll.bak
2. Copy the new SP3 patched termsrv.dll to \Windows\System32 folder
3. Run the included registry patch â€œts_concurrent_session_patch.regâ€ (by double clicking it), it will update the relevant registry values which are relevant to the concurrent sessions support.
3. Restart windows.
if you are currently using Terminal Services, you will need to start windows in safe mode before you can overwrite the existing termsrv.dll files.