Well, it might be malware.
But, first, lets see if we can get your icons back.
First, press Ctrl + Alt + Delete > Click Processes tab > See if you can find explorer.exe.
If you can not find it, try going File > New > Type in Explorer.exe > Press Enter
See if that brings back the icons. If it does, Please try this workaround (you will need your Windows® XP SP2 CD or an integrated SP3 CD if SP3 is installed).
(In the event that you do not have a Windows® XP CD with SP2,(or SP3) you will need to 'borrow' one from a friend or colleague, as the manufacturer's "Recovery Discs" will not work in this instance.)
Insert the Windows® XP CD in your drive. (Hold down the Shift Key to prevent it from starting.)
Go start > Run ...in the box type in sfc /scannow …please take note of the space between the sfc and the /.
This is the System File Checker...it will scan all the Windows® core system files to ensure that they are in their respective correct places, and if not replace them from the CD.
During the scan you may be asked to Insert the CD, if this happens just go retry and let it do its thing.
One important point: While sfc is running, it is not advisable to do any other work, or have any browsers/programs running on the computer, until the scan is complete. (This process will generally take around 45-65 minutes to complete).
--If you do see explorer.exe in the processes tab--
Try a Repair Install.
How to perform a Repair Installation of Windows® XP.
Two things are needed here, just a bit of old technology, an ink pen and a piece of paper to write down any special settings that might have to be changed back after the repair-installation is completed.
Please Note: Performing a "Repair Installation" in this manner should not delete any Personal Files, it should 'repair' the core of the installation but to be safe with your data you should follow the next two paragraphs.
You might have to remove the hard drive from this computer and install it in another computer as a slave drive and after it is able to be accessed by Windows on that computer you will have to manually backup all of your important data that you have to another media like CD-R's, DVD or external hard drive. Then when this is done return it to the original computer as a master drive on the primary IDE cable.