Looks like some slipped through the cracks on SP1 upgrades with BTARN installed. If the process hangs with the command box open check the setup log. It may look like this.

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[08/13/10 11:42:12] Package Microsoft BizTalk Accelerator for RosettaNet 3.5 is installed.

[08/13/10 11:42:12] Package code is {394EFEF0-99D2-4DBA-9446-0664E62ACEAF}.

[08/13/10 11:42:12] Performing post-installation custom actions. 1 actions to perform.

[08/13/10 11:42:12] Starting process "C:\Documents and Settings\All Users\Application Data\Microsoft\E-Business Servers Updates\Updates\UninstallSP1\Install.exe" …

The problem is “xcopy” is trying to copy a file and it already exists. This causes a hang condition. The fix is to let the install continue by killing the “xcopy” process in task manager. This should let the install finish. If the process remains in the hung condition after a minute or so kill the “install.exe” process and un-install the SP.

If you have to re-install avoid the issue by deleting the file “C:\WINDOWS\system32\AcceleratorsInterop.dll “. Then run the SP again. Be sure to read the install document with the SP. It has several required manual steps like un-enlisting the BTARN orchestrations.