WLM not starting msmail.dll not initialised

[wapwap]

Hi there, I'm having a problem with Windows Live Mail not starting. I get an error message telling me it may not be installed correctly (error: 0x80041161) and msmail.dll may not be installed correctly.
<ignore>It has been working fine up till now. It does open when I browse to the program folder (rather than using start menu or desktop shortcuts), but it doesn't load any of my account settings, contacts or messages.</ignore> -Edit: I've just realised I'd opened WinMail not WLM.

If it's relevant I've had problems with other programs (mostly Microsoft) starting up. So far today I've had problems with:
Excel 2003
Word 2003
Internet Explorer 7
Windows Contacts
Windows Live Photo Gallery
Blocklist Manager

I'm also having problems installing the latest Windows update (KB942615- Cumulative update for IE7), getting the error number 80073712.

Since I'm having so many problems at the same time I don't know where to start! Thanks for your time.

 

[wapwap]

Nevermind, formatted hard drive and reinstalled Vista.

 

[wapwap]

Sorry to bump this but this problem has resurfaced so ignore my last post. It's the same programs. It makes no difference whether I start them from their folders or shortcuts.

I tried repairing Windows Live Mail, Photo Gallery and Writer but got an error message telling me they weren't installed properly. Same when I tried to uninstall. They were working fine!

What could be causing this? What should I do? I've only just started to get my programs and files set up again after my last format so don't want to have to do it again.

Edit: I forgot to mention when I try to reinstall Windows Live Suite I get the error message:
"Code: 0x80070641
Description: This installer service could not be accessed. This can occur if the Windows Installer is not correctly installed. Contact your support personnel for assistance"