Why does safari stop opening web pages after a while in use?

Question

Since upgrading to Lion, my imac (Intel) 21.5 works fine for most of the time, but frequently when using Safari to browse the internet, it will stop accessing pages, either from new searches or from history - the blue loading bar in the address panel starts, then stops. Safari itself keeps working, new tabs can be opened, history can be checked, etc. Checking the Wi-Fi shows that it is still connected, and other PCs and ipods in the house can still access the net, showing it is not a net or router problem. Restarting the machine does not usually cure the issue, only shutting down for a long period, eg overnight, when it generally starts up fine again.
This has been happening almost since I upgraded 2 months ago, but not every time we use Safari.

Answer 1

You can do some basic Safari trouble shooting by:
Safari - Reset Safari
Safari - Empty Cache
You can also be just low on RAM. As a general rule your system should have about 500MB or more of FREE RAM. To check to see how much your system has open Activity Monitor - System Memory Tab and look for the amount of free RAM. You can find AM in Applications - Utilities - Activity Monitor. Remember to check when you are seeing a slow down otherwise the information will be meaningless. The graphic will look similar to: