Cannot Open URL

I just opened my iTunes and had the pop up about the update 7.4.3 so I clicked for it to update and it's telling it "the URL could not be opened." So I clicked "Start, All Programs, Apple Software Update" and am getting a long error message about,

"SoftwareUpdate.exe - Entry Point Not Found

The procedure entry point (long list) could not be located in the dynamic link library SoftwareUpdateFiles.dll"

Can anybody help me?