Why/how is svchost.exe using 6.5GB of memory?
svchost.exe is the process that runs all your Windows services. One of them has gone mad apparently. Right-click on svchost.exe and select "Go to Service(s)". That will tell you which service it is, and you can use Services Manager to restart or disable it if you don't need it.
For a better description with nice screenshots check out:
- How-To Geek: What is svchost.exe And Why Is It Running?
Per your update, you can check out a couple of those services:
- CscService: Related to the "offline folders" feature of Windows. Do you use that?
- UxSms: Related to Desktop Window Manager. Try disabling Aero, see if the problem occurs.
After splitting suspected services to separate processes I was able to identify Network Store Interface Service (nsi) to be the cause of memory leak in my case (Windows 7).
There is ten-page thread about this issue at http://answers.microsoft.com/en-us/windows/forum/windows_7-system/nsi-memory-leaks-fixed-yet/f3c3e9db-36a7-45df-9dbd-de9455378498.
It mentions a couple of hotfixes available for download on demand:
http://support.microsoft.com/kb/2847346/en-us
http://support.microsoft.com/kb/2950358/en-us
There is also a similar fix for Vista and Server 2008:
http://support.microsoft.com/kb/2743187/EN-US
Another option: Use Process Explorer.
It can be downloaded via Microsoft TechNet.
It displays all running processes, you can easily see which svchost.exe is using CPU or RAM resources, to track down which service is runnning wild.
Tip:
When hovering the mouse cursor over the 'svchost.exe' entries, all services associated with this process are listed in an infotip window.
Alternatively, select the process, click "Properties" and choose the "Services" tab.