First, make sure you've got the most recent firmware installed on the router AND make sure all network adapters on the computer have the most recent updated drivers..Sleep mode issue are common on both ethernet and wireless adapters and updated drivers can fix that.
Next, makes sure the video and audio drivers are up to date as well.
Next, antivirus/firewall programs can also cause the issue. Make sure you have the most recent program updates for your computer..Program version updates can provide "fixes" for the issue.
Make sure to install all the Critical Updates from the Windows Updates site. Some fixes are included.
Next, have you tried using a different browser? It may not make a difference but both Outlook Express and Internet Explorer come from the same core.. Try Firefox or some other free browser to see if it can connect correctly using the other browser.
Free Firefox Download
http://www.mozilla.com/firefox/
And last but not least, stop using the power saving modes.. All our computers are either on or off but nothing in between. We've found that some computers just done use it well.
Hope this helps.
Grif
When first booting up all works then after the monitor goes into power save mode and returns to active both IE and Outlook Express freeze IE says page not found and Outlook Express states unable to locate server. After I reboot all works fine until the monitor goes into power save mode,running XP Home SP2 2.4 ghz pent4,512mb RAM Linksys wireless router, 256k wireless internet, also does the same thing when the router is bypassed , and I don't use hibernation Thanks.

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