First let's make sure your computer is clean of malware go to http://www.hijackthis.de/en and download from upper right hand corner.  

Run hijackthis and post the log.

eb

A few finidngs:
These arn't going to be the cause of your problem but should be addressed:
O2 - BHO: TW_BrowserHook - {1E1B2879-88FF-11D2-8D96-FFFFAC95951F} - C:\Program Files\WinScheduler AS\mtwbho.dll (file missing)  
Unnecessary (deactivated) entry that can be fixed. mtwbho.dll - Macro ToolsWorks, http://www.pitrinec.com/toolsworks.htm  

O2 - BHO: (no name) - {7E853D72-626A-48EC-A868-BA8D5E23E045} - (no file)  
Unnecessary (deactivated) entry that can be fixed. This entry was classified from our visitors as good.

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O4 - HKCU\..\Run: [ToolKit] "\" -L -S /silent Unknown application. <- this is an unknown and may be dad.  If you don't know what it is you should remove it.
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O8 - Extra context menu item: =>&Spanish - http:\wordreference.comesjiees69.htm  
To be fixed if the entry '=>&Spanish' is unknown. Entries shown in the menu that pops up when right-clicking into the Internet Explorer. Unknown entries should be fixed.

O15 - Trusted Zone: wumt.westernunion.com  
If you didn't add 'wumt.westernunion.com' to your trusted pages, it should be fixed. If you did not add these pages to your trusted pages, they should be fixed.

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O23 - Service: dlbc_device - - C:\Windows\system32\dlbccoms.exe Unknown service. (dlbccoms.exe) <- another unknown and should be removed if you don't know what it is.
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O23 - Service: @%windir%\system32\inetsrv\iisres.dll,-30007 (IISADMIN) - Unknown owner - %windir%\system32\inetsrv\inetinfo.exe (file missing)  
Very safe Fuzzy Algorithmcheck (3.

O23 - Service: @%windir%\system32\inetsrv\iisres.dll,-30001 (WAS) - Unknown owner - %windir%\system32\svchost.exe (file missing)  
Very safe Fuzzy Algorithmcheck (3.07 / 5.00),

O23 - Service: @%windir%\system32\inetsrv\iisres.dll,-20001 (WMSvc) - Unknown owner - %windir%\system32\inetsrv\wmsvc.exe (file missing)  
Fuzy Algorithmcheck (3.28 / 5.00),  


And one NASTY
O23 - Service: World Wide Web Publishing Service (W3SVC) - Unknown owner - %windir%\system32\svchost.exe (file missing)  
Safe Fuzzy Algorithmcheck (2.85 / 5.00), Nasty


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You can select the above items in hijackthis and allow it to try to fix them or you can try combofix http://www.bleepingcomputer.com/combofix/how-to-use-combofix

eb

Try the system file checker http://www.tech-recipes.com/rx/2231/vista_run_system_file_checker

eb

How needs sound...
You should be able to get sound back by reinstalling the drivers for your sound card.

eb