Verify that the dlls:

extmgr.dll

occache.dll

are v7.0.xxx

Verify that the registry keys:

{692F0339-CBAA-47e6-B5B5-3B84DB604E87} points to extmgr.dll

[HKEY_CURRENT_USER\software\microsoft\windows\currentversion\Shell Extensions\Cached]

Value:

"{692F0339-CBAA-47E6-B5B5-3B84DB604E87} {93F2F68C-1D1B-11D3-A30E-00C04F79ABD1} 0x401"

01 00 00 00 xx xx xx xx xx xx xx xx xx xx xx xx

If it's not present it's not a problem but if it's present and starts with 00 manage add-ins dialog won't work.