After running update, itunes store won't open and then itunes closes

Question

I have tried reinstalling and changing some settings as advised on other forums. The last couple of updates have all gone badly with me investing hours in repairs. If I didn't have an IPhone I would have already abandoned itunes - but I am stuck.  I am at 5 hours of wasted time on this one issue. Please help!
Here is the info from my computer:
Problem signature:
  Problem Event Name:          BEX
  Application Name:          iTunes.exe
  Application Version:          10.5.2.11
  Application Timestamp:          4ee0844d
  Fault Module Name:          MSVCR80.dll
  Fault Module Version:          8.0.50727.6195
  Fault Module Timestamp:          4dcddbf3
  Exception Offset:          00026b72
  Exception Code:          c000000d
  Exception Data:          00000000
  OS Version:          6.1.7601.2.1.0.256.48
  Locale ID:          1033
  Additional Information 1:          898e
  Additional Information 2:          898e26c3db74dcd51af7432eeb771a80
  Additional Information 3:          c87d
  Additional Information 4:          c87d5e3c827baf7f73becf484eae2011

Answer 1

I went into the admin log in for my computer and changed the "Data Execution Prevention" setting to "turn on DEP for all programs" which now allows my admin log in to get to the itunes store - but I cannot open it on other log ins - which is where all my music is stored. Additionally, I do not have the option of changing my DEP settings on my non-admin log ins. The real frustration here is that everything worked FINE before the update. Any ideas on how to fix this?