I use Ubuntu 9.10 64-bit with SeaMonkey 1.1 and Firefox 3.5 (versions from the repositories).

Since I installed Ubuntu 9.10, Flash buttons and videos don’t respond to clicks. This makes lots of websites unusable.

I tried several things, as installing the 64-bit version from Adobe but it didn’t resolved the problem in Firefox and caused SeaMonkey to crash on websites using Flash.

I had the same problem on two computers, both using 64-bit karmic koala:
1 – Core2Duo, nVidia, upgrade from 9.04.
2 – Pentium 4, ATI, fresh install.

So this is not a problem from nVidia proprietary drivers as I read somewhere.

Here’s the solution that worked for me for all browsers on both computers:

– edit
the file /usr/lib/nspluginwrapper/i386/linux/npviewer

– add “export GDK_NATIVE_WINDOWS=1” (without quotes) before the last line of text

Hope it works for you!
smiley

PS: Mr Adobe, please release a stable 64-bit Flash plugin!