There are many possibilities, and it's really difficult to sort them out without actually sitting at the machine.
As has been suggested, I'd try downloading Spybot and running that; it will find some things that other programs have not. It doesn't sound like a hardware issue - just so we're clear - if it's physical, it's hardware. If it's a program, it's software. It does SOUND like a virus or similar is mucking up your system.
Second, make sure you go to the respective websites (windowsupdate.microsoft.com, officeupdate.microsoft.com, adobe.com and hp.com) and download and install any relevant software updates, drivers or patches. When companies fix a bug in their software, they make the fixes available but they don't tell anyone about them. It's up to you to see what's there - usually under the Downloads or Support section.
See if that works.
Third, one thing you might try - and it's entirely dependent on your own level of comfort - is to run a selective startup.
Click on the Start button then click on Run (just below Search). In the box that opens, where it says Open: type msconfig and click enter.
Now, every program that loads when you start Windows will be listed in here. Ignore that for a moment. On the 'General' tab, under Startup Selection, click the dot beside 'Selective Startup' and then uncheck all of the boxes under that. Then shut down the computer, count to 10 slowly, and then turn it back on. That will do what's called a 'clean boot'. None of the possible conflicting devices will be loaded. When the computer boots up, you may get an error message telling you it can't find something or other. Ignore it for now. Now try to repeat the problems you're having. The difficulty with sporadic problems is that they never occur when you want them to.
However, if you have NO difficulties, then go back to Start/ Run and msconfig will probably be listed there again. Hit Enter again, and this time click on Diagnostic Startup. Click Okay, shut down the computer once more, wait 10 seconds, then turn it back on, and try to repeat the problem.
Now, if you're still okay, you know you have a conflict in one of the programs that have loaded.
Run msconfig again, click on Normal Startup, but this time follow that by going to the tab on the right (at the top of the window) that say Startup. This is a list of every program bit that loads with Windows. Uncheck them all, then click Okay, then shut down, reboot, etc. If everything works, go back and check one or two of them, starting at the top and working your way down, shutting down and rebooting each time, until you come across the one box you check that causes the problems to reappear. IF that happens you know where your conflict lies. Again, only you can decide your comfort level with doing this and it might not solve the problem.
It's a long process of trial and error, and you may find yourself wishing you simply reformatted your hard drive and started over. If you do go that route, start with a clean install of Windows and then reinstall programs - one at a time - from the original CD's if possible. Remember to go to the respective company websites and find updates, patches and new drivers where appropriate. Don't simply reload everything from the backup you made or you'll simply return your computer to the state it was in.
And my apologies for the inappropriate comments from another earlier poster.