I had a lot a problems with this error my self so i thought i would post the soloution here encase any one needs it
If your computer starts up with a msnp32.dll missing error you may notice that your network neighbourhood or Network places icon has gone.
To get past this problem uninstall the client for Microsoft Neworks(located in network settings funnily enough) then restart the machine.
Next go back to the Neetwork settings in control panel and click add and reinstall the Client for Microsoft Networks again. It should then prompt for your Windows disk and then it should restart.
After starting up again the problem should be fixed.