When the URL http://apronet.hu/aprohirdetes/szorakoztato_elektronika/televizio_tv_keszulek_lcd.php is loaded in the background (and in some other random cases), Flash malfunctions. The following symptoms are exhibited: -Flash animations fail to play sounds, and the animations immediately freeze when they attempt to play any sound, and -Youtube videos stall after 2 seconds (other Flash-based video sites stall at a different time, e.g. the Hungarian site IndaVideoBomb stalls after 5 seconds). To get back to normal functionality, the offending tab must be closed, the cache cleared and Firefox restarted. Steps to reproduce: 1. Open the above URL in a tab. 2. Wait for the page to completely load (until the favicon appears on the tabstrip). 3. Open a new tab, and load a Youtube video on it. It will stop after 2 seconds, and during that 2 seconds, play no sound. This bug is known to exist on Windows XP and Windows Vista. I seem to remember seeing it on Linux once or twice as well, so it is likely cross-platform.
If you report bugs about plugins always include the used plugin version.