Foxyproxy not working

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Upgraded to firefox 3.6.6. and now when I am trying to run foxyproxy, I am getting the error "Error writing settings file: [null]. Ensure the path exists and that FireFox has write access, then restart FireFox. FoxyProxy will not function until then.
I have looked at the following thread already but cannot find the answer to this issue here - http://foxyproxy.mozdev.org/drupal/content/foxyproxy-error-writing-setti...
please advise
Thanks

Hello, does the problem

Hello, does the problem still persist?

Unfortunately yes. Am still

Unfortunately yes. Am still not able to use foxyproxy and am getting the same message. Please advise.
Kind regards

Update to issue

Hi,
It now seems that the proxy in itself is working but the error dialogue box still appears everytime i try to use the proxy or turn it off or basically perform any function with it but the proxy when enabled does actually work - so it is just the error box which is an issue....
Thanks

Hello, Is your disk full?

Hello,

Is your disk full? Are you on a read-only system (like a Live CD)?

Eric

Hi Eric, No - loads of space

Hi Eric,
No - loads of space on the machine. It is a windows 7 installation and foxyproxy was working fine but recently when i did an add on update (prior to the latest version), it just stopped throwing that message.
I tried to follow the advice on http://foxyproxy.mozdev.org/drupal/content/foxyproxy-error-writing-setti... but found that this extensions.foxyproxy.settings does not even exist in my machine.
I have now updated the new machine with the latest foxyproxy add-on but still the same message.
Again, firefox version is 3.6.6, Windows 7 Starter, with approx 80GB free on my hard disk. I am logged in as the administrator - so no issues around that.
Thanks
Amit