Today, I noticed a javascript error shown by Firebug while surfing my own (WordPress) blog. Firebug always reported a “Components is not defined” for

this.xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");

in wp-includes/js/tw-sack.js.

It turns out that tw-sack.js was not the only file affected – also post.php and wp-gears.js showed this error.

I googled this – but I found nothing helpful.

So I tried reinstalling Firebug. That seemed to have worked fine at first: the mysterious error was gone… but just for a while. It was back after a few minutes – and I don’t reallly know where it comes from. The only thing I know is that I just had a WindowsUpdate. IE on the other hand shows no Javascript error.

The error doesn’t seem to affect the functionality of my blog, but I hate these red-and-white Firebug Xs!

Update:
After rebooting and clearing the cache etc., everything seems to work now – the error hasn’t appeared since.

Is this a Fire”bug”? Or is it related to the recent Windows Update for October ^[1]? Or is it just because there were some failures or incompletely loaded files within the cache, and clearing it was all there was needed?

I dunno.

[Update from 2008-11-20]

Hmm… I just recently installed FF 3.0.4 and Firebug 1.3.0b3 – and the error seems to have disappeared.

Update:
It’s back! I changed nothing! This is some odd behaviour, I must admit…