lvo55,
After some research, it seems that there are issues with the wireless driver for your Dell model. Dell has updated drivers on their site which you can download and install.
Go to:
http://support.dell.com/support/down...&fileid=233125
Then click "download now". Save this file to your desktop. Once it's downloaded, launch this and allow it to install the updated Intel Pro Wireless drivers and related software. These new drivers should resolve your connection issues.
- John