Becoming member has nothing to do with this mate, someone is obviously hacking your account. Something that jagex cannot fix only you can. The only way jagex could fix this would be locking your account until your computer is keylogger free. I personally think its a keylogger my mate hacked a ALOT of people and this sounds exactly like a keylogger but as you said you just got a new comp, have you put any documents from your old computer to your new computer? Maybe you had a external hardrive that got infected and you have transferred the infected files to your new computer. Do you have any friends that come around they could have placed a keylogger manually. Do you visit any websites that seem dodgy or have you downloaded any files since you have used your new comp, have you ever been having a convo in msn or one of the web messangers and downloaded anything from people? I suggest you scan your whole computer then delete any cookies and tempory internet files then backup any files you want and re-install the version of windows/linux/apple you are using.