Many things can cause a PC (from Cybernet or otherwise) to run slower than it has in the past or even to crash.
The most common cause is a full hard drive; if the hard drive is full of data (85% or more) it can cause a PC to operate much slower than normal. The quickest fix for this is a larger hard drive, or backing up data to an external media.
The PC may also have an old Operating System installation; it is recommended to reinstall the OS at least once a year. This is because over time old and removed programs leave traces behind (a file here, a registry entry there) that can cause a build-up of unnecessary information on a computer. There are many tools available to help alleviate these concerns, some of which are built into Windows. Always be sure to uninstall programs via the Add/Remove Programs option in the Control Panel, or if the program created an Uninstall icon this can be used as well.
Be sure to run Disk Defragmenter on the machine once a month at the very least. This feature is built into Windows, and available in the System Tools folder of the Start Menu.
Another tool to use frequently is the Disk Cleanup option, also located in the System Tools folder. For advanced users, the program CCleaner can be used in tandem with Disk Cleanup to clear out old files no longer being used. Though System Restore is available, this option is not recommended as it may inadvertently restore to a non-working configuration of Windows. System Restore also takes up disk space, returning us to the most common cause.
It is also recommended to run Memtest86+ to ensure the RAM in the unit is not faulty. If using a USB Flash Device or Floppy disk that is formatted as a DOS Boot Disk, please download the file labeled "Pre-Compiled EXE file for USB Key (Pure DOS)." Once downloaded, extract the *.exe file to the root of the SD Card. When the machine boots to the DOS C: Prompt, type the file name and press enter to begin the test. The test will indicate when it has completed; if it fails many red lines on the screen will be visible and it is ok to stop the test at any time. If using a USB Flash Device that has not been formatted as a DOS Boot Disk, please download the file labeled "Auto-installer for USB Key (Win 9x/2k/xp/7)." Running this file while a USB Flash Device is connected to the computer will format the device as a DOS Boot Disk that will load Memtest86+.
To ensure the Hard Drive has not gone bad, we suggest running Seatools, a tool provided by Hard Drive manufacturer Seagate. Choose to download the DOS version, and choose either floppy or CD ISO image, whichever is most convenient.
If the system is infected with spyware/malware (random pop-ups, changed home page, etc), be sure to have antivirus software installed and updated. There are many tools available for combating spyware/malware, many of which can be found for free. Windows has its own anti-spyware tool, Windows Defender, which is included with Windows Vista and Windows 7. Windows XP users can download Windows Defender from Microsoft. Microsoft also offers free antivirus protection via its Security Essentials application, available for download here. For serious spyware/malware issues, we recommend following the steps at the following site - Majorgeeks.com Malware Removal Guide. To resolve further spyware/malware issues, please follow the directions for posting at www.majorgeeks.com and post a question/comment in their forum.