MacOS – a good web browser for OS X 10.4 Tiger

There's a reason why Apple appears to onlookers to be so anti-Flash, and it's because Flash sucks on Macs (it may also suck on other OSs, but I don't use them enough to be knowledgeable).

What to do about it depends on what browser you use (your question doesn't say, as Mozilla's Plugin Check isn't FF-only):

• Safari - the answer is ClickToFlash. Honestly, C2F is something that should just come pre-installed on every Mac.
• Firefox/Camino - As Ken mentioned in a comment, you want the FlashBlock extension.
• Chrome - use the FlashBlock for Chrome extension.

As has already been said: you can get along fine on almost all sites without Flash. Here's some additional recommended reading, both of which are from John Gruber at Daring Fireball:

• Going Flash-Free on Mac OS X, and How to Cheat When You Need It
• Masquerading as Mobile Safari to Get Websites to Serve HTML5 Video to Safari on Mac OS X

Make sure you don't have any network proxy settings - you might want to try creating a totally new 'location' in System Preferences -> Networks, select AirPort, click Advanced, then make sure that none of the Proxies are checked.