Windows Crashing after several minutes

Windows has been getting progressively worse for a while now, but for the last few days has been horrible, and now it is crashed completely.

Again, I've had some issues for a while, but they were alright before this.
I'll just describe what has brought me to this immediate point.

Got home this evening and tried to open a website on Firefox. The page would not fully load. I tried opening it in other browsers, and that worked a little better. I pulled up the task manager to see if I could see anything strange.
I noticed that the CPU usage was at 100%. I checked the processes area and saw that svchost.exe was really cranking away and that rundll32.exe was sometimes pulling up multiple entries of syswow64\WININET.dll, sometimes six or seven of them.
What is happening now is that Firefox is useless, and after a little while the computer crashes, sometimes to BSOD and sometimes just cuts off.

I did recently deal with what looked to be a virus in the temp folders that was opening hidden webpages and slowing everything down. I cleaned out temp entirely and it went away and worked fine.

I do not have a Windows 7 restore disk.

Please help me out

Now I just located a message hidden in my drive on a txt doc that says t my data has been encrypted and will be unusable if i don't go to a certain website and pay for the encryption key.
I checked and it does look like some my files are now changed, but not all.
Looks like I got a virus...

I have it already and the free trial has elapsed.

EDIT: I'm running it now.
Is there anything that can be done about the encrypted info?
It doesn't look like anything critical is gone, but I'd like to get everything back.

Malwarebytes found, quarantined, and deleted two infections.
A trojan hiding as svchost.exe and a general malware of \fonts\1s11Y.com

I am afraid that the scan and deletion of those problems didn't fix things.
It almost looks like the svchost is doing the same thing again. Computer crashed when I tried to start Malwarebytes up again. I am doing it in safe mode with networking and running again.
What else can I do?

I do think that the registry of Windows might have some errors now.