I just wanted to offer a solution to IPN issues.
Today, I noticed that my IPN script was no longer working. Payments were coming in, but customer information was not being stored in my database. I triple checked everything, but was at a loss what the issue was.
Then I remembered that I turned off the "KeepAlive" setting on my apache web server last night. I read an optimization guide that under heavy traffic loads, it can really help by disabling that setting.
I can tell you right now that if you (or your host) disables the "KeepAlive" setting, your IPN script will no longer work.
I'm hoping this info will save someone from the same headache that I went through this morning.
