On one level, if she's good for the money, what's the problem? She's contributing more money to the poker economy, and that's good for all of us, including you.
On an entirely different level, yes, it sounds to me like she has a compulsive-gambling problem. This is a big problem for her and the people she is close to. A compulsive gambler presents to friends and family all the problems we associate with addictions and substance abuse, with the added complication that compulsive gamblers can burn through much more money than other sorts of addicts. A heroin addict's next few fixes cost only $10 to $100; a compulsive gambler can go through thousands of dollars in an hour.
How close are you to her? If you are close enough to be within the blast radius when she goes off, above and beyond any ties of friendship with her, your interest of self-protection plays a role here. You might simply want to get outside of the blast radius, i.e. cut your ties to her and put some distance between you. Or, you may want to work to make her explosion less likely.
I know a number of compulsive gamblers who turned to poker because it is a game that smart people can win. They still have a jones for risk, but try to feed that jones with positive-EV bets. One approach may be to "help" your friend by showing her how to be a compulsive gambler who wins rather than one who loses. From what you say, though, she doesn't seem to be amenable to this approach.
If you're close to her and you care for her, another tack might be to set up an
intervention with the assistance of other people close to her, as well as possibly an addiction and recovery professional.
Lastly, she's good for the money now, but if things don't change, the day will come when she asks you for a transfer, you shoot her the funds, and she doesn't pay you back. The only way to prevent this is for you to stop transferring funds to her.
In your situation, what I would do would be to stop transferring funds. I disagree with others in the thread: don't make up some story about how the site warned you about "suspicious transfers". Tell her the truth: you won't transfer her any more money because you are concerned she may have a gambling problem. It stands a significant chance of ruining the friendship, and at the same time it stands a noticeable chance of being her wake-up call. If she keeps on as she is going, the friendship is in trouble anyway.
I know this is grim advice, but it's a grim situation. There is, however, more hope than some of the other posters make out.