the screen freezes and the large hour glass icon appears.this can happen at any time.

It could be a variety of reasons such as incompatible Add-ons, incompatible toolbars, lack of system resources (RAM), malware, Java problems, etc. Hard to say without knowing the error details.

First run your resident security products such as antivirus and antispyware applications. If everything comes up clean, try uninstalling your toolbars such as Google or Yahoo through Control Panel, Add/Remove Programs. If the issues continue, go to Tools, Manage Add-ons and disable each one by itself to see if one of them is the culprit. If you are still having troubles, update your Java by following these steps.

Assuming that you are in the Administrator account, go to Control Panel, Add/Remove Programs and uninstall everything that says J2SE, Java and Java Runtime. Reboot (some computers require a reboot to complete the uninstall process). Then go to the site below and download the most recent version of Java.

Afterwards, in IE, go to Tools, Internet Options, Advanced tab and scroll down to the Java section and tickmark the "Use 1.6.2 (version changes with each update) for applet". Click Apply, Click OK and reboot (a reboot is required for some computers for the settings to stick).

http://www.java.com/en/download/index.jsp

Finally if everything above has been ruled out, you probably have a system resources problem. You can see if your computer can handle more RAM by going to Crucial.com and running a scan.
http://www.crucial.com/index.asp

It's important to note that everything takes RAM. Not only security products (such as active anti-spyware, anti-virus and firewall) eat up memory but your operating system, active browser windows, running applications (such as Word, Gaming, Messenger, Photoshop, etc) and malware

Get yourself either the latest version of Internet Explorer or download the free browser from Firefox.