jscript runtime error

Hi
I'm running Win 7 fully updated, but have recently started getting this error msg at various times but always when I'm not actually at the PC. Programs running are Outlook 2013, Explorer, Win Media Player (fully updated), Picasa & Firefox, along with MSE & Roboform in the background.

The error springs up in a box stating: object doesn't support this property, & requires 2 clicks to knock it off whereupon it then doesn't return for maybe 3-4 days or longer, but eventually it does pop up again.

It's not causing any obvious problems but am curious to find out what might be provoking it. Google searches only seem to discuss actual scripting projects etc rather than just normal usage of the PC, so weren't a lot of help .

Thanks
TKR

Hi Rich
Appreciate your speedy response :) - wouldn't surprise me if it was indeed my FF that was the problem as I have TONS of add-ons - female failing so my brother tells me LOL!! But as you've stated, many are probably not requisite so I'll have a trawl through them & dump any that seem dodgy.

Would this type of error msg possibly be flagged up in the Windows System log do you reckon -didn't think of checking it yet but wondering if it might reveal some info?

Thanks guys
As I said, it's not like it's causing any major issue - just curious about a likely contender to try & put it to bed. But appreciate all the helpful info. :)