I think mount2073 is looking for some very basic information about how and why these things happen and how he might avoid these kinds of problems. The advice to discuss it with an OPM is excellent, most Outsourced Program Managers are professionals that want you to succeed.
ABW is a valuable resource and the searchbox up at the top of the page helps you look things up so that you can read as much information as you care to about the topics that concern you.
Linkshare is kind of on everyone's pit list for now after having allowed OneCause's toolbar in time to hurt honest affiliates at their busiest (holidays) time of year.
These toolbar affiliates deliver lots of sales and can look impressive on paper, but they haven't actually brought you one new customer. They just claim credit for all sales by popping in the merchant's shopping cart just in time for the commission. They don't just steal from other affiliates, they steal much more from merchants because all the traffic you used to have is now theirs too. Imagine paying a commission for a sale made when shopper Sam types in your URL just because shopper Sam installed the OneCause toolbar so he could donate to his favorite cause with every purchase.
Be wary of what looks like some super stats on prospective affiliates, know who your partners are and how they are promoting your program. Set your terms and plan to police them. Read up on what's acceptable and do discuss with an OPM. Be prepared to police your program because the network
fees do not cover program management at all so if you aren't going to manage your program, the affiliates will. The network makes more money with parasites in your program because they convert non-commissionable clicks into commissionable clicks.
Be sure your program carefully and completely spells out the terms under which you agree to pay a commission; be fair, but be careful. Plan to read a lot. Look at the "Becoming a Merchant" forum here at ABW, there is excellent advice there too. Good luck.
Just bumped into rematt's post with all those good useful links: