I'd check yer internet connection and make sure it's rock solid with no interruptions. It sounds like that's the general problem. Also, yer computer bein' as old as it is could play another factor (I heard somewhere that computers over 5 years of age begin' to "die" in a sense, less I'm mistaken there). I'd also check 'n make sure ye have enough bandwidth- internet bandwidth, to access the game. This can be done by checkin' in with yer internet company. I say this because often times when I run out of bandwidth, since I am unfortunate and do not have unlimited like some, I can no longer access any online games without disconnectin' time and time again, back to back like ye have explained.
I personally believe it's yer computer and/or not a strong internet connection. Mayhaps ye'll need to obtain a new software if push comes to shove should ye really wish to play FeralHeart badly enough. T'is all I know on the subject.