Disappearing downloads

Hi guys, I'm new to newsgroups so I don't know how to tell if this has been
answered before and I'm not seeing it. My apologies.

I just built a new system with a new install of Vista 64 home premium.

I cannot download anything! In IE, when I download a file, it goes through
the process and then the window dissapears and the file is not on my system.
I used my other comp to put firefox on a flash drive and installed that, but
firefox has a similar problem. Everything that downloads gets grayed out in
the firefox downloads list & the file is not in the downloads folder. I'm
guessing this is a security "feature" of vista but I can't figure out what
to do.

I've turned off UAC, changed the setting in Misc in security options to
allow dangerous files, changed folder views to show hidden... I'm lost. And
really regretting the purchase of vista.

Thanks in advance