There is an e-mail message with the subject "PC Error Removal Alert" from "Hotmail Users" that contains a link to the website knotbultsahn.net. This website will redirect you to the website (www.ascentive.com) that contains a software with the name SpeedScan_setup.exe. The software is suppose to speed up your computer but, a lot of consumers have complained that this product is a rip-off.
The subject line of this e-mail message may change but , it will contain the text: "Tune up your PC for better performance".
Updated June 22, 2012: This e-mail has another subject line: "3 Steps to Better PC Performance"
This is how the e-mail looks:

If you click on any of the links in the e-mail message, you will be taken to this website:
http://knotbultsahn.net/mt10711ua/spicetracks /digaroos9984001/sortylights /shooz/chachahm.asp
and redirected to www.ascentive.com.
This is the website that you will be redirected to:
http://www.ascentive.com/run/click/@163754222878 4/products/SP/select3_finallyfast_hydra_download.html

This is the file that you will be prompted to download:

Here are complaints from some customers at ResellerRating:

Never download any executable files (files ending with the '.exe' extension) from websites that you are not familiar with.