bad relative url parsing + fell for bad bot trap + goes after urls with "guestbook" in it is same user agent as IE 7 beta running on Windows Vista (beta). Vista is released with IE 7 (not a beta!). This user agent was seen before the release of Vista.
aggressive bot (multiple requests per second) 2007.05.07: seems to be a malicious browser-extension that explicitly requests disallowed pages (via robots.txt) that are linked by user-visited page to harvest e-mail-addresses and guestbook-forms. 2005.09.20: came from 188.8.131.52, querystring correct 2005.09.11: came from 184.108.40.206, converted querystring to lowercase