Multiple Adobe Flash Problems

Question

Hi. I'm facing multiple Flash-related problems for quite some time.
Troubles
1. No sound in Flash. Be it youtube or any other streaming site.
2. Occasional and quite frequent 100% CPU Usage while using flah content
3. Flash content often goes choppy. Often as slow as 0.5fps.
Solutions Attempted
1. Re-installed OS multiple times.
2. Tried older/newer versions of Flash and browsers.
3. Tried a few general solutions from the web.
4. Played with settings etc.
Specs
AMD Athlon 2400+ 2.0GHz rated @ 2.4GHz. 1.12GB DDR1 RAM. Onboard VIA S3G KM400/KN400 Video Card with 64MB shared memory. 80GB HDD. Windows XP SP2. Firefox 3 [Tried all versions, and other browsers too]. Flash 10 [Also tried Flash 9].
I didn't have the problem an year or two back, and since then, there has been no change in my hardware. Maybe an upgrade, but definitely not a downgrade.

Answer 1

Some troubleshooting for flash player:
http://kb2.adobe.com/cps/191/tn_19166.html
If you follow all the steps, this will usually lead to http://kb2.adobe.com/cps/408/kb408620.html
The second link includes steps for developers and then steps for users (not sure why they didn't list the users section first). Skip to the users section and follow those steps.
This will fix many flash errors, however there are still some flash videos that are just broken. You should record the URL of the sites that cause your flash player to crash IE.
Here are my troubleshooting steps for Internet Explorer:
Internet Explorer 7 and 8 both include a "no add-ons mode" which is useful. My suggestion would be to attempt running in "no add-ons mode" and notice whether or not the speed improves. If so, open IE as normal, click tools and then click manage add-ons. Disable Add-ons you don't recognize and don't need or use. I personally don't use search toolbars b/c I can easily type in bing.com and then search. This is usually faster than running a bunch of add-ons anyway. After disabling the add-ons you don't recognize/want/use, look for the column that depicts load time. Anything that takes a long time to load is slowing down your browser, disable it if you can live without it. Finally, any add-ons that you chose not to disable should be updated if available. Check the site that belongs to the vendor listed in the Publisher column of the toolbar for instructions on how to update their product. Many updates require or work better if you uninstall the old version of the product first.
If you still experience crashes and slow loading, you should consider resetting IE. After resetting IE, notice the change in speed. You can then start to install the add-ons you want, but if it slows down again, you should disable the culprit that you just installed.
This is just me personally, but I prefer to run with minimal add-ons. After resetting IE, all i re-install is the latest version of my Firewall/AV suite's browser protection, which truthfully, isn't necessary, but I've not had problems with it.
If you continue to have audio issues,  Microsoft has a fix it which will fix/diagnose many audio issues: http://support.microsoft.com/gp/no_sound
You've also mentioned that you've re-installed your OS. Have you updated all of your drivers? Many times vendors don't place the latest versions of their drivers on Windows Update, so it may be necessary to go to your PC manufacturer's website to find these, or even directly to the hardware manufacturers sites (which is the method I prefer).