Wireless adapter won't complete install

I have a Dell Dimension 4300, 512 Meg RAM, running Windows XP (home) SP1. I use a Linksys AP/Wireless Router with a 4-port switch. I have 3 PCs connected (one wired and two wireless) but have not been able to connect the Dell Dimension. I connected this system to a home network through a USB wireless adapter (Linksys WUSB11) and it worked fine for a month. Then, I got nervous about security and changed the SSID for the router. At this point, the wireless adapter would no longer connect. I deleted the associated software and deleted the drivers from device manager. When I went to reinstall the software, the last steps of the installation failed. I got a message that Windows could not install the device because it could not find the necessary file. The message named the file. I could see it on the install CD, but installation never got past this point.

The same thing happened with a different Linksys wireless adapter and with a D-Link PCI wireless card. All three products work fine on another computer in the house.

It seems to me that something in the OS is causing the install to fail. Dell Tech Support recommended repair/reinstall of the operating system. I did that but the same problem persists.

I don’t know if this means anything, but the system is keeping track of each failed installation attempt. It now lists the D-Link card as wireless adapter 19. Can anybody help me solve this?