Windows installer errors

Hello, I am having a number of problems with Windows installer:
I have:
Windows 7 home premium
64 bit
Intel Duo CPU 2.20GHz
Purchased from Best Buy 12/09 with Windows 7 already installed

Yesterday I could not install my new printer, I had a problem with windows installer. After doing a search for the error message MSI.dot4wrk40 with no results, I called Dell tech support. After about 2 hours on the phone I was told to back up all my data, and given instructions on how reinstall Windows 7. I first went through and did all the Windows updates, then the software updates. After this I had to reinstall all my programs that is when the headaches began.

NOW I cannot install a number of my programs, programs that HAD previously been installed and working on the computer, including Itunes, Quickbooks pro 2009, HP printer software and others. They all bring up error messages regarding windows installer. I should mention that some installed just fine.

I have checked and have Windows ® Installer. V 5.0.7600.16385

I am at my wits end, I don't know what to do next and frankly found Dell Tech support unhelpful and frustrating.

Can anyone here recommend a fix?

Thank you
Jenny P

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