I have spent all evening trying to get it off. Any ideas?
First things first, give SuperAntiSpyware a run and clean off anything it finds, reboot. If that don't do it, try restoring your computer to a date before you noticed everything started happening using System Restore. If that still don't do it, let us know and we'll go from there.
The thing that's on your computer is not a virus but more properly termed "Malware". It's a fake. Everything about it is fake and is designed to trick/force you into going to a web site and paying money for removal. These do not install on thier own - you or someone using your computer was tricked into installing it on your system by way of a pop-up. As long as you didn't run the wrong automated cleaners to try to remove it, it can be reversed. Clicking on the fake warnings can cause deeper Windows' settings changes (search redirects, web site redirects) that will be difficult for you to remove. Running some automated cleaners can cause damages, as well.
I've removed hundreds of these and I don't normally give my trade secrets away, but here's a quick way to remove an early infection. Plug in via Ethernet, boot to Safe Mode with Networking then open System Configuration Utility (Start>Run>msconfig). Go to the Startup tab and look for your Malware file and it's installed directory. These things disguise themselves - take your time and look at each entry carefully. Look at both the name and the command location. You are looking for a random name, number, or maybe even a common name with the directory in your user files. They most always put themselves in a hidden or protected system folder (also hidden) in the User Files section. Look for these folders as part of the command location for the candidate Malware file in your Startup list: AppData, Temp, Local Roaming, Roaming, or ProgramData.
Take your time and you'll eventually find it. There may be several depending on how indiscriminately you have clicked "OK" on script-generated pop-ups while on the Interwebz. Once found, go into Folder Options and unhide hidden files and folders and also unhide protected system files. Navigate to the location of your nasties and delete them. Also uncheck the entry for them in your Startup list. Feel free to delete the entire contents on any Temp folder - not the folder itself but only its contents.
Now open Internet Explorer and go to Tools>Internet Options>Connections tab>LAN Settings. If the box next to Proxy Server is checked, uncheck it. Actually, this Window should not have any checks. Apply, OK, Close
Hopefully deep damage has not occurred and you will be able to both install and update MalwareBytes. If it updates, run the Quick Scan, once finished click Show Results and let it clean anything it finds. If MalwareBytes won't install you need professional help. If it installs but the Malware's settings changes have prevented its ability to connect with the update server, you need professional help. If it installs but doesn't run, try going to the install directory: Program FilesI(x86\MalwareByts\ and renaming mbam to something else and running it from there.
After a successful scan/clean with MalwareBytes, it will prompt you to reboot and Vista/7 must be told to allow the last part of the cleanup to be allowed to run - this is done by way of notification in the Taskbar on the right side. After this, download HitMan Pro and do the "one-time scan". After it scans, you can click a link to allow free 30-day activation.
If none of this works, I strongly suggest you backup. Copy all of your data (pictures, music, documents, favorites) to an external drive off of your PC. I personally know of no techs besides myself that can repair deep damages that causes things to not run, search redirects, will not allow access to certain web sites and your best bet is to do a Windows reinstall after backing up your data while in Safe Mode.