A "good" Internet worm and a new malicious mass-mailing computer virus are creating an enormous amount of network traffic, slowing some corporate systems, security experts said on Tuesday.

The Internet worm -- called MSBlast.D, W32.Welchia or W32/Nachi -- started compromising computers on Monday and has overwhelmed some corporate networks with its aggressive scans for vulnerable hosts. Meanwhile, a new variant of the mass-mailing Sobig virus, called W32/Sobig.F, took off on Tuesday, swamping many companies' mail servers.

The double whammy caused problems on some corporate networks but not for the Internet at large. Sobig.F disrupted email systems at the Massachusetts Institute of Technology, while the MSBlast variant, Nachi, disrupted the ticketing systems of Air Canada and the corporate networks at Lockheed Martin.

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