Dell Studio 1558 (Early 2010) - Manual (Page 133)

Maintenance Tasks (Enhance Performance and Ensure Security)
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2 Select the drive you want to defragment and click Analyze to determine if
you need to defragment the disk. Click Defragment to go ahead and
defragment the disk.
NOTE:
You should not use your computer during the defragmentation process.
Detecting and Repairing Disk Errors
1 Click Start→ My Computer.
2 On the File menu, select Properties.
3 On the Tools tab, click Check Now.
4 Select the actions you want to perform and click Start.
Scanning for Viruses and Spyware
Computer viruses and spyware are hidden software that corrupts your files or
gathers information from your computer without your knowledge or consent.
Computer viruses affect your computer’s performance, and can destroy data.
If your computer has Internet access, you should install antivirus and
antispyware programs.