Explanation: You bought and installed a hard disk but the system is seeing it as smaller than it actually is supposed to be.
Diagnosis: This is not really a problem at all, but actually a discrepancy in the way drive sizes are reported. Hard disk manufacturers use decimal megabytes (1,000,000 bytes) in their advertising, and BIOS auto-detect routines use the same measure. Other software, especially most disk setup and partitioning utilities like FDISK, use binary megabytes (1,048,576) in their reporting. The difference of about 5% is what you are seeing.
You can open the case and take a looksie
