OK, I assume you didn't deliberately change anything. If you did, start checking the drivers for your latest hardware before doing anything else.
Symptoms: Stable Windows 7 x64 system suddenly has HDD indicator light on solid (or nearly solid). Happened suddenly without warning, re-occurs within a few minutes after booting.
PC will freeze for at least several seconds at a time. CPU activity is high. Task Manager is slow, hangs frequently and tells you nothing useful. Process Explorer seems to show System process (PID 4) taking lots of CPU, but no other details - no real indication which process is actually hogging your hard drive.
Turning off antivirus doesn't help. Acrobat may complain about a "serious error" when started and/or freeze up. Inability to use Disk Management tool. Shutdown takes tens of minutes, if it happens at all; might freeze on "Logging off" or "Shutting down".
Cause: Something probably broke. Chances are your DVD-RW drive, CD-RW drive (if those exist anymore) or a secondary hard disk/SSD in your system has bit it. This can cause the HDD indicator light to stay on permanently even though the PC is actually not trying to do anything in particular.
(As a guess, it's probably that "secondary" high-capacity hard drive you stuck into your PC when you did your first SSD upgrade. You don't use it much and tend to forget it is there. It's probably old, old, old by now.)
If you're smart enough to have placed your virtual memory swapfile on the pseudo-dead drive, you may have additional problems.
Poking around in "My Computer" may tell you which drive is at fault. It may show up but be inaccessible; it may be partly accessible but might disappear later. You will probably not be able to run any kind of disk check on it; trying will result in an Explorer hang.
Solution: Manually shut down and disconnect the suspected offending drive or burner. If possible, try reconnecting with a Dock to run Seatools or other diagnostic utilities and/or to copy files off the drive. (You are backing it up, right? RIGHT!?!?!?! Stupid!)
Note that maybe the SATA port went bad, rather than the drive. So be sure your replacement is a known-good drive and/or use a different port.
(Why this affects Acrobat is beyond me and is just one more example of why that is a poorly coded program.)
If it's not the above, then you're down to shutting down programs to see if you can find an offending process. Good luck.