Just wanted to chime in since I'm having this issue as well. I updated all modules and core for D6, and the problem seems to occur only on Google Chrome.
It also appears to have started happening once we switched from an Apache server to a Cherokee server.
It still works fine on Firefox, as well as Safari (thus it doesn't seem to be a webkit issue). But Google Chrome is not having it...
I'm still looking into it and will post if I find anything. Otherwise help is appreciated =]