Children's sci-fi/horror book about boy going into computer, part of series

[...cats?]

I didn't read this series, but I saw it in a library in the early 2000s (probably between 2003-2006) and I've been trying to find it again. I don't have any plot details. The series seemed kind of similar to Goosebumps, except that the same character (a middle school boy) was the main character in all the books. His name may have been Zach. The book I remember most clearly was about the main character entering a computer. The cover showed the boy (maybe wearing a baseball cap and a red jacket?) getting sucked into a PC computer.

[Kris]

cats?, that's a good start. Please add more plot details (entering a computer, cover image) to the topic header (title). We have thousands of book requests.

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[...cats?]

Anisha_book_lover wrote: "Maybe "Keeper of the Kingdom" by H.J. Ralles?
"

This isn't it, thank you though

[...cats?]

Anisha_book_lover wrote: "A couple of very long shots....
1. "User Unfriendly" by Vivian Vande Velde

2. "Discordia: The Eleventh Dimension" by..."

Thank you so much, but none of these are the book I remember. I can't say what the color of the cover was, but I think the art style was similar to the pulpy/cartoon-y style of a Goosebumps cover and the computer was sitting on a desk with hypnotic swirls coming out of it. I have no idea if the boy went into a video game; I didn't read the book, only the back cover, and I can't remember much of it.