Which web browser is this occurring in?
In all likelihood it'll be the current page you are attempting to view, or a pop-up page generated from the current page you are viewing.
The error itself is implying either graphic intensity of the page being loading is preventing the page loading in a timely manner or something in the page - a graphic or javascript, or flash is failing to load.
Try clearing your caches of all save images, cookies, etcetera. That will likely reduce the alerts.
You can also modify most browsers configurations to prevent these kinds of situation, but to get help with that we'll need to know which browser it is you are experiencing this issue with.
If you could provide some details about your graphics card or onboard graphics chip and the current version of the drivers for these, that would help too. There may be an update for the driver that would also help improve things for you.
Regards,
Regedit32