I get this message during JetBrains YouTrack 6.0 Setup on my Windows 7 PC:
"The installer has encountered an unexpected error installing this package. This may indicate a problem with this package. The error code is 2738."
Based on some suggestions online, I registered vbscript.dll with administrator privileges (also tried deregistering it NOT as an administrator, then registering it as an administrator), but this didn't resolve the issue.