APPCRASH in Explorer.exe

hi all,
anyone got any ideas how to cure the prob below. It happens when i right click a folder or icon (eg. to delete, or copy or explore). Right click is fine if used on desktop, or copy and paste text.
At the time this started, i was useing Vista Ultimate so banged in an upgrade to Win 7 to see if it would cure it. Nope. Tried all the recommended scans, (malwarebytes,superspyware etc). My thinking is its something to do with the content menu opening, but im hanged if i can find a cure.
thanks
nigel

Problem signature:
Problem Event Name: APPCRASH
Application Name: Explorer.EXE
Application Version: 6.1.7600.16385
Application Timestamp: 4a5bc60d
Fault Module Name: kernel32.dll
Fault Module Version: 6.1.7600.16385
Fault Module Timestamp: 4a5bdaad
Exception Code: c0000005
Exception Offset: 0005085b
OS Version: 6.1.7600.2.0.0.256.1
Locale ID: 2057
Additional Information 1: 1d32
Additional Information 2: 1d32409995138d855a2b9bb446ccc159
Additional Information 3: bd92
Additional Information 4: bd92becdde1f92cda004092bfde37325

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