Error When Trying to use Steam... Please Help!!

I have been trying to use Steam on my computer but for some reason it comes up with an error that reads, +*"SteamStartEngine(0xbfffdd58)failed with error 1:CMultiFieldBlob(pSerialized): Badfield-Extends past Blob"*+

Does anyone know what this means...
Please help... Ive tried reinstalling it already, and it just comes up with the same thing. Cant get ahold of Steam for help...
Thanks!