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You can’t access shared folders on another computer if that computer isn’t actually on. Don’t uninstall and reinstall your PCMCIA card, stupid.
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If you can access the internet, but not the shared computer, then the problem exists between the router and the desktop. Don’t uninstall and reinstall your PCMCIA card, stupid.
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As a corollary to the above, always check your cables first. Especially if you have cats. You’re not getting that hour of your life back.
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It’s a firewall, it’s designed to keep people out. Don’t be surprised when it does it’s job, and you can’t access the shared folders. Don’t uninstall and reinstall… oh forget it.
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It seriously rocks to be able to lie on the couch and surf the net.
Wireless networking… cables…? That might be your first hint that you’re doing something wrong! 
Seriously, I’ve found that MS OS upgrades will hose anything my hardware should do.
My story is that I like reinstalling hardware, and I’m sticking to it. 
If it’s wireless DSL, count on it frequently being inaccessible for hours on end. Stick with dial up when possible.
(Or maybe it’s just this particular gateway.)