Someone using Proxy Cache Browser accessing my site for more than 37 hours

[jiam1]

http://www.screenshots.cc/original/40230/2nr5c

Appended above is the screen shot of the ip of the person who has been accessing and reloading my guestbook since yesterday.
Visit length : 37 hours 44mins 15 secs
Reloads : 256 times
Browser : Proxy Cache

Could someone advise what this person could be up to and
what measures should I take?

Many thanks in advance.

[jiam1]

The person has since left after staying for 41 hrs 58min 56secs and reloading 288 times.

Never come across someone staying for so long on my guestbook site which has less than 200 pages. Worried that he/she is trying to hack my site.

And also because I have never heard of a Browser by the name of Proxy Cache
(The ones that I am aware of are IE, Firefox, Opera, Netscape, Safari)