faulty SP2 install?

[sj_robertson]

My system has recently started exhibiting signs of instability, including showing the BSoD last night with a bad_caller_pool error, so I ran sfc /scannow to determine whether I had any memory issues. This came back showing that certain system files were corrupt, as well as their back-up versions, including "MSOERES.dll", "IMJPST.DIC", "IMTCPH.IMD", "Vertigo.dvr-ms", "NlsLexicons004e.dll" and "NlsData081a.dll".

I decided to look into the cause of this and looked back at my installed updates, only to find that Windows Vista Service Pack 2 (KB948465) failed. Despite this, my Welcome Center shows my system as running SP2, even though I can find no evidence to suggest that it was ever installed correctly... From what I have been reading, I also cannot replace the corrupt system files with my original disc, as that contains SP1.

Any ideas whether this could have caused the problems I am experiencing, or if I can sort this problem out without having to do a full re-install?

How can I verify whether SP2 was installed correctly (despite the message to the contrary in Windows Update) so that I can look for the solution elsewhere?