Itunes was unble to load dataclass information from sync services reconnect or try again.
Environment: Windows xp sp3, itunes 8, iphone 2.2
itune 8 was considered to have the virus or Trojan horse behavior, simply turn off your antivirus software the following functions: Trojan acts judged and interception, IE leakproof wall, Trojan download intercept. Then everything work well
This was what works to my situation, hopes it can help you!