Ares Ultra..
I used to have Ares (no not ultra but it was, i think the version before..) and it used to launch on start up (well not exactly launch, but sit neatly on my task bar) but it always would connect on start up.
I unfortunately no longer use ares (Im thinking of using it again soon though) but I recommend that you have a look around in teh setting in ares to see if you are actually connecting on start up (or as soon as you launch the program) because this is often the case.

Also, you haven't installed any new fire wall software lately have you?
If you have I suggest you see if Ares is granted access to the internet. Most firewall software informs you if an application wants access to the internet (which you can give the application access with a click or two) but if you haven't been informed I suggest you take a look around in your fire wall's settings.

XP SP2 shouldn't be a problem at all though. Most of the time when Ive downloaded software, its been recommended that you have SP2 (For W.i.n/d/o/_w_s XP users). I run SP2 aswell and I ahve never had any software issues because of this.

I have another suggestion. Go to the site where you downloaded it from and see if the site has any Q&A's or FAQ's that might help. As a matter of fact, Im on a site right now and it does say thats Ultra has connectivity problems but I can not find anything on how to fix them.

One last thing, if you cant fix the problem give Ares Galaxy a try. Its almost the same, in fact, its exactly the same from what I can see.

Let me know if you fix the problem

<3