I don't think starting a new acct would help. The problem is with your computer, most likely, not necessarily this site. It's software related, Operating system updates, cache size, conflicting browsers, Java, Flash or Quicktime, etc.
I was having issues seeing images or players with my old computer. Things I couldn't view in Explorer, I could see in Firefox and vice versa. There's a chance that the issue was my video card was giving out....so rather than go to the trouble of fixing all that on an already old computer running on xp (another possible culprit, a soon to be unsupported operating system), I spent surprisingly little money on a significantly superior laptop, with newer and updated software and operating system
I think after time, your computer's hard drive and software run into errors that accumulate eventually, some things you just can't fix, without having to backup and then reformat your hard drive and reinstall your Operating system and software, depending on your knowledge and/or patience of researching the problem online.
(BTW If you are using explorer, have you tried changing to "Compatibility View"? This link describes where it is:
Compatibility View
I have to use it when I go to Idolforums. For some reason, some sigs disappear for me unless I view it in "Compatibility View". It switches your explorer browser to a setting that views websites designed for 'older browsers' better. With it switched 'on' I can see the sigs, and some images 'normally', otherwise I sometimes see a missing graphic icon or a "your image is too large" warning for some sigs.
Error messages when posting images, videos, etc // Problems playing video
If you do that, you will have to re install ALL your software, not just Windows....and that's a decision to not take lightly. Also, it's not easy to do so if you want to do it, (I would advise against it, without help), you should get someone that really knows their way around a computer to do it for you, as well as back up all of your files.