Cannot Open Programs/Files

I have had a virus for about 3 weeks now. When I first got it i did a scan and found a trojan virus. I fixed that, but now when I try to open any program, it brings up an "open with" box and lists various programs. If i try to open internet explorer, then select it on the list of programs to open with, it brings up the open with box again and again, then asks me to download programs such as "iexplore.exe". To get on the internet and write this I had to go through control panel, then program defaults and selected the website links. HELP PLZ!!! email answers prefered.