If you experience any kind of the foresaid issues there is a possibility for malware problem. First check whether you have installed dell recommended anti malware programs like McAfee, Norton Antivirus, and Trend Micro PC–Cillin. If you already installed Run the anti-virus program and keep the firewall and windows updates and other recommended settings ON.
If expired download the updated version from Dell Online Store and install ASAP. or Call the Nearest Dell Service Center from Sulekha Yellow Pages.
If you have any Windows Boot Problems during your computer start up. Here is the tips to fix Windows Boot for Dell