We have a campaign up and running that collects clicks. Over 50,000 clicks have been recorded from 2 different IP addresses, both with the user-agent's set to AOL9.0. I was wondering if there is a known AOL9.0 + AJAX issue or if someone is just masking their user-agent.
UA String
Mozilla/4.0 (compatible; MSIE 7.0; AOL 9.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; MDDC; BRI/1; .NET4.0C; BRI/2)
I do believe AOL proxies their users. Verify this by running a whois on the source IP addresses. If they are registered to AOL, then it seems likely those are proxy servers. Also check your logs to see if that UA string appears in any significant amount from other IP addresses.
As far as AJAX issues in the AOL browser, I do remember a long time ago bumping in to an issue where the response being served with Transfer-Encoding: chunked would cause the AOL browser to barf. Specifically, the chunked encoding is not 'decoded', so the hex length value is passed to your script, causing a JSON parse error. If your script expects a response and retries if it gets an error, it is possible that your code is going into an infinite retry loop.