ERR_INVALID_RESPONSE when exporting

I get an ERR_INVALID_RESPONSE error when trying to export large amounts of inbound messages. Right now I have 7800 messages held hostage in Flamingo. It only concerns 1 of my Contact Forms so I am allowed to export inbound messagges from other forms where the number of messages are way less than the 7.800 messages. I got my hosting company to set the timeout up to 10 minutes but I still get the ERR_INVALID_RESPONSE error. I can also export the Address Book without a problem. Could it be a memory issue? Please help.