I've just been through about 48 hours of not being able to post or even comment, and Blogger wouldn't let me post either, so I am feeling a wee bit vulnerable just now.
If it was a virus or a trojan as
cesario suggested, I ran several scans and never found it. But this morning it got so bad that I couldn't connect to the Internet at all, so I restarted my modem and router, and now it seems... okay.
There is, however, an odd mushroomy smell coming from somewhere. *sniffs air suspiciously*