Why are you running Firefox 1.5 which is very very insecure? you should IMMEDIATELY update to Firefox 15.0.1 as the version you are running is very very ancient and out of date. Once you update try to install plugins again.

Update Firefox to the latest release

Install Firefox on Linux

Warum läufst du Firefox 1.5, die sehr, sehr unsicher ist? Sie sollten sofort auf Firefox 15.0.1 aktualisieren, wie die von Ihnen verwendete Version ist sehr sehr alt und nicht mehr aktuell. Sobald Sie zu aktualisieren, um Plugins zu installieren.

Which Linux distribution do you have?

I don't think that you can run modern software on that device.

• http://www.parkytowers.me.uk/thin/Igel/3210/index.shtml

• http://www.mozilla.org/en-US/firefox/3.6.28/system-requirements/
• http://www.mozilla.org/en-US/firefox/15.0.1/system-requirements/