Weird yui/lib requests

I just happened to notice some strange HTTP requests coming from one IP address. There were hundreds of requests per minute, all going for dom-min.js, container-min.js, modules/search/SearchBlock.js, yahoo-min.js, and maybe some other .js files, all preceded by an increasing number of /yui/lib/ . Here is what one request looked like:

"GET
/gallery/main.php?g2_view=comment.ShowAllComments&g2_itemId=16610&g2_return=/gallery/lib/yui/lib/yui/lib/yui/lib/yui/lib/yui/lib/yui/lib/yui/lib/yui/lib/yui/lib/yui/lib/yui/lib/yui/dom-min.js
HTTP/1.1" 200 4871 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;1813)"

There were hundreds of these requests per minute, and the number of /yui/lib/ directories increased with every request.

I don't know if it was related but at the same time this was happening my server's load average went from 0.51 to 48.32, then went back to normal after I blocked the IP address.

Does anyone know what's up with those weird yui/lib/yui/lib requests?

Gallery version = 2.2.3 core 1.2.0.5
PHP version = 4.3.10 apache2handler
Webserver = Apache/2.0.50 (Fedora)
Database = mysql 3.23.58, lock.system=flock
Toolkits = ArchiveUpload, Gd
Acceleration = full/86400, full/86400
Operating system = Linux server 2.4.22-1.2115.nptl #1 Wed Oct 29 15:42:51 EST 2003 i686
Default theme = matrix
gettext = enabled
Locale = en_US
Browser = Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.11) Gecko/20071127 Firefox/2.0.0.11