As the spell is currently (and publicly) written, I agree. It is overpowered for an Advanced ability. If the spell was resistible possibly with Resist Magic (a 4th Level discipline ability) or it were possible to investigate the source and track the caster down, possibly with Greater Sense Magic (an ability of equal level) or even if another Wizard with access to the spell could counteract the power (albeit at the same cost) I believe it would balance out the power.For the record, any spell that gives a PC the ability to anonymously and irresistably cripple another character is both broken and dumb.
From another standpoint, Curse/Remove Curse appears to be a logistical nightmare. It requires a member of the staff to track down the victim immediately in order to maintain a level playing field. I would hate to cast the spell on someone only for them to discover their misfortune hours after I paid the cost.
I honestly think that the ability is an awesome idea. Balance issues aside, it allows for some incredible role play. Unfortunately, I also believe it detracts more from the game than it adds.