Before doing any hardware replacement or sending it to your technician. Check the software before checking the hardware. Run an updated antivirus and check for spyware/malware which may encounber memory and overwork the CPU. Also defrag the hard drive, but backup your data before doing so. Removing dust is always a good idea. I use Spybot Search & Destroy for removing and checking for adware/malware, it may be only that the problem. You can download Spybot on security.kolla.de.