Use your laptop on a Hard surface so the fans and case can dissipate the heat the right way. If you use it on your lap you have your body heat + the laptop heat, which will make it hotter. http://gadgetwise.blogs.nytimes.com/2009...-ways-to-cool-down-your-laptop/?_r=0
You can open your laptop and clean the dust out of it. Also you can reapply the thermal paste to the cpu. Make sure you clean your old paste off. Use a coffee filter to clean it off. That should make it run a little cooler. How to Apply Thermal Paste
Go to Control Panel > Ease of Access > Ease of Access Center > Use the computer without a mouse or keyboard > Uncheck "Use On-Screen Keyboard" option > Click Ok. On left panel Change administrative settings options > Click and check Apply all settings to the logon desktop > press Apply.
Make sure you are not using a static IP Address. Go to Network & Sharing, click on the network you are trying to join. Next right-click on Properties. Then double click Internet Protocol Version 4 TCP/IPv4. Make sure you are obtaining your IP address and the DNS server automatically. Same with alternate configuration. If that doesn't work uncheck IPv6 in the properties tab.
This is not for your specific model but it will be pretty much the same steps. Get a replacement and your golden. Dell OptiPlex GX260 Main Fan Replacement http://www.amazon.com/Dell-Inspiron-Studio-8000-X755M/dp/B007T9867E Your actual DELL manual. http://downloads.dell.com/Manuals/all-products/esuprt_desktop/esuprt_inspiron_...-580_service%20manual_en-us.pdf