Hi  Shannon,

Please update the wireless drivers  for your  Dell Studio XPS 1640. You may click the link below to access the Dell Support Website:

http://dell.to/QjjZDA

Hope this is helpful. Please revert in case of any further queries.

Thanks and regards,
Prateek_K
#iworkfordell 

For easy access to drivers, manuals and product updates, please visit our Support Site. 

Updated and still not helping

Hi Shannon,

Thank you for your reply.

I request you to kindly check the Wireless Power Management Mode on your computer.

The power management setting is basically a  power savings mode. There are six levels of power savings, numbered 0 through 5. Level 5 provides the greatest amount of savings (i.e. uses the least amount of power, and thus, is less taxing on the battery). Level 0 disables power savings mode. An advantage of disabling power savings mode is that it provides the greatest Wi-Fi network performance.

The Power Configuration Management in Windows 7 is accessed through the Control Panel Power Options > Advanced Settings > Wireless Adapter Settings > Power Saving Mode > On battery/Plugged In.

You can select the power plan that you want to customize and then choose settings that reflect how you want your computer to manage power.

Hope this is helpful.

Please revert in case of any further queries.

Thanks and regards,
Prateek_K
#iworkfordell 

For easy access to drivers, manuals and product updates, please visit our Support Site.