1397 WLAN card drops network drives

Machine acts fine after boot attaching to network drives and internet.  Within the first 15 minutes to one hour, network drives start becoming inacessible and eventually crash Explorer requiring a hard reboot.  Typically, either sleep or hibernate causes the problem immediately as the machine awakes.  Internet access works throughout.  Unchecking "Allow the computer to turn ofF this device  to save power" in driver for 1397 WLAN causes problem (yellow alert icon) with Microsoft Virtual WiFi Miniport Adapter. 

Have operated an XP wireless laptop on this same network for years without any of these types of problems.

Have tried all of Rick's suggestions in another thread:
Update the firmware in your wireless router. Manufacturer's website, make & Model needed.
Broadcast SSID(You may want to change this to make it easier to connect)
Use WPA-PSK(TKIP) Security(WPA Personal). Most wireless devices work best with this type ofsecurity.
Mixed b and g mode(n if available)
Use channels 1, 6 or 11. Most devices work better on these channels. (I use channel 11)
Save and exit. Power everything off for 30 seconds. Power everything back on, wait 30 seconds, now try to connect.

Studio 1747
Windows 7 Home Premium
Core i7 Q720
4GB RAM
Radeon HD 4650
ST9320423AS ATA
Linksys WRT54G router

Appreciate any help you can offer.

Steve