My friend asked me to look at her Acer Aspire laptop with Vista Home Premium as it is no longer playing DVDs. I found that Windows Media Player would not launch. I found this thread, which contained a number of suggestions, none of which solved the problem. Here is what I tried:

• Tried running WMP via desktop shortcut, QuickLaunch bar or going to Program Files\Windows Media Player\wmplayer.exe. In all cases, wmplayer would launch then terminate immediately (verified through the Processes tab in Task Manager).
• Tried running wmplayer.exe as Administrator. The UAC dialog would come up, I'd approve, then wmplayer would launch and terminate immediately.
• Uninstalled all non-Microsoft media programs except RealPlayer, iTunes, QuickTime, Acer Arcade (the laptop owner uses all those apps).
• Tried running Program Files\Windows Media Player\setup_wm.exe as Administrator, it launched but said that a newer version of WMP was already installed.
• Deleted the "Windows Media" folder located under %userprofile%\appdata\local\Microsoft then tried starting WMP - wmplayer would launch and terminate immediately.
• Register wmp.dll by typing "regsvr32 wmp.dll" in an Administrator cmd window then tried starting WMP - wmplayer would launch and terminate immediately.
• Run "SFC /SCANFILE" in an Administrator cmd window - get an error message that it found invalid system files and could not fix them, so look at the log file cbs.log. The log file shows that there are broken files associated with Windows Sidebar (which the user does not use) but none relating to WMP.
• Log off to safe mode and run "SFC /SCANFILE" in an Administrator cmd window again - same results.
• Try to download and install XP WMP - the microsoft.com site recognizes the OS as Genuine and allows the download, but when I launch the installer it says the system is not Genuine. Clicking the link directs me back to IE where I can authenticate the system as Genuine. The installer still fails to recognize the system as Genuine. It is a Genuine Vista installation.
• Try to run this update (KB931621). The installer said it did not apply to the system.
• Set Windows Media Player as default in Program Access and Defaults. Same results.
• Tried running "for %a in (%systemroot%\system32\wm*.dll) do regsvr32 /s %a" in an Administrator cmd window - same results.
• Went to this Knowledge Base article (947541) and ran the Microsoft Fix It. The Fix It ran successfully, but WMP would still launch and terminate immediately.
• Multiple reboots in the process of doing all of these steps.
• After all this, looked in the Application and Security logs. No events pertaining to WMP were logged.

The computer was preinstalled with Vista Home Premium and I have the Acer backup DVDs which will reimage the drive. I do not have Vista install DVDs. Reimaging the system is not an option. I'd also rather not restore the system to an earlier point unless it's absolutely necessary.

What else can I do to repair or reinstall WMP?