More than 500 students on the Penn State computer network have been affected by a computer bug that has recently forced them off the university's network.

Kathy Kimball, Information Technology Services security operations and services director, said it is hard to tell where the problem originated.

"It's a 'blended threat,' " she said. "It works more like a worm than a virus, but it's neither one. It's a complicated issue."

According to Symantec's Web site, a blended threat combines characteristics of computer viruses, worms, Trojan horses and malicious codes.

Kimball said a blended threat might include keystroke loggers, which keep track of all typed passwords, credit card numbers, and other secure information.

She added that students need to protect their computers by using personal firewalls and limiting their use of file-sharing programs to download video games in addition to music files.

"There's been an influx of students with insecure computers," said Cliff Rodack, residence hall network coordinator. "Once security sees that the computer is infected, those students get shut off the network until their computer is reformatted, patched, and have virus protection put on."

Rodack said students should back up their files in case their computers need to be reformatted as a result of an infection.

He added that infected computers must be reformatted, or they will not be allowed to return to the network.

"I would have lost everything," Morgan Macenka (sophomore-English and journalism) said.

"I have a digital camera and all my pictures are on my computer. It would have been like my house burning down, everything would have been gone."

Macenka said that after she got a virus last semester she visited Residential Computing (ResCom), but workers said they would have to reformat her computer.

"Over the summer I was able to get it fixed without having to reformat it, but it was kind of expensive," she said. "They transferred all my files and cleaned them out."

Rodack said using this method increases the probability that the computer will be re-infected because remnants of the malicious code may still exist.

Michelle Markowitz (sophomore-business) said she has had computer problems for about a week, but backed up her files so she could get her computer fixed.

"I didn't do it all at once, but it's taken me a couple of days," she said.

"I have to go to the computer lab to do everything. It's a big inconvenience."

Rodack said that because so many computers have been infected, students need to pick up their machines quickly to allow ResCom to help more students.

"Students are giving us cell phone [numbers], which we can't call," Rodack said. "Students really need to come down and check to see if their machine is ready."

Rodack said students who know how to reformat their own machines could do so.

They are given a checklist to follow, including the installation instructions of the proper anti-virus software.

Once the checklist has been completed, a technician will look at the machine to verify it was completed correctly and the student will be allowed back onto the network.

"This is a temporary policy because there are so many infected computers," he said.

Rodack said students should use automatic anti-virus updates and download patches, operating system updates and programs that combat pop-up advertisements and spyware from the Internet as they become available.

Kimball said students need to do their part to make sure their computers are free of any harmful elements acquired from the Web.

"The university is doing what it can," she said. "The user has to be responsible for his or her own security."