Hye,

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It could be your internet connection
i had a 3g wireless modem for my laptop thinking it was good for business however the service optus provided here in australia was shit and timed out regularly on numerous sites. If i was able to get to gmail at all i had the same problems you are experiencing. Gmail was the most affected site in my experience.
Firstly rule out the computer as the culprit by connecting to a different network if possible and trying gmail there, if it is successful the problem lies with your isp. Contact them and complain about their 'contention ratio'. I am led to believe that in some countries of the world ISP's are mandated to supply contention ratio's to customers and prospective clients on request. However her in Australia it is not and the average call centre employee doesn't know or feigns ignorance. However without more details i would say the contention ratio of your ISP in your area is to blame.
n.b. Contention ratio for the record is the number of requests/users trying to access a restricted number of available slots from teh exchange, out into the wide world of the internet or to the ISP or however that particular ISP works. Basic explination.
essentially its like having a 10lane on ramp but only 2 lanes on the highway, everythings all good while the onramp isn't getting many motorists. but when that on-ramp gets busy all the cars can get on the highway, it just takes time. And sometimes this 'time' can take longer than timeout intervals.
Complain to your ISP

Try this one here http://kielaldea.blogspot.com/2009/07/gmail-just-keeps-loadi­ng-but-never.html

be sure to leave some comments on my blog so that i'll know if it solved your problem

Good luck