strange 404 errors

I was checking my error logs just now, and I was noticing I keep getting this strange error with some of the hits.
404 not found /%3C
I looked, and I don’t see any broken links, and my stats don’t show any specific page reffering to this. I assume this is something wrong in my php. Anybody willing to take a look, here’s the link eliswindow.net.
thanks.