Whos Online weird User Agent va;ie

Just saw this in Whos Online -

User Agent: %4D%6F%7A%69%6C%6C%61%2F%35%2E%30%20%28%58%31%31%3B%20%55%3B%20%4C%69%6E%75%78%2 0%69%36%38%36%3B%20%65%6E%2D%55%53%3B%20%72%76%3A%31%2E%37%2E%35%29%20%47%65%63% 6B%6F%2F%32%30%30%35%30%32%32%31%20%46%69%72%65%66%6F%78%2F%31%2E%30%27%20%41%6E %64%20%38%38%3

Assuming some type of bot - just curious if anyone knows whos crawling? Or has something else caused this? Other current entries look 'normal'.

If you 'URL decode' it you get this:
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.5) Gecko/20050221 Firefox/1.0' And 88%3

But I do not know what to think of it.