I've never heard of that error before. I probably won't be much help beyond regular troubleshooting steps.
Obviously since it is working on one computer and not another it isn't the device itself, it must be software somewhere causing the issue.
I always recommend when having issues to uninstall the software, clean out all files left behind, and reinstall it from scratch. So that would mean running the uninstaller, then after restarting the computer, deleting any folder named "Sprint/Sierra/Novatel/etc." (depending on the manufacturer of the card), then restarting once again. After that, while the device is not plugged in, install the software, restarting the computer. Then plug the card in and let windows find and install the drivers on its own. Once it is done installing the drivers and associating them with the card, start SmartView and try to connect. That has fixed 99% of the mobile broadband issues I have ever seen, regardless of device or carrier. As always make sure you are using the latest version of the software, at the moment it is SmartView 2.28.
You say it is the 3G that isn't working correctly, right? You can also try connecting through the modem with Windows directly to see if it is the SmartView software having the issue or some driver/access issue. You can do this by opening up the Network Connections and directly connecting using the Mobile/Sprint/CDMA connection. If it connects and you have internet, there is something with the software, if not then there's some issue with the way the card is interfacing, which probably means a driver or peripheral lock of some sort. In this case I recommend opening up the Device Manager and seeing if anything has a yellow exclamation point or red X listed.
Have you used the troublshooting tips provided on the Support web site? This may help a little. http://support.sprint.com/support/device/Sprint/3G
I seem to be having the opposite problem of most people. I have a U300 card that I use on two different computers. Both 4G and 3G work just fine on my work laptop (which runs Windows XP). However on my personal laptop (which runs Windows Vista), I cannot get 3G to work. I live in an outlying area that does not have 4G coverage, so this is very frustrating to me. When I try to log on, it tries to get 4G, then reverts to 3G. But when I try to connect to the 3G I get an error message 797 (saying something like it cannot find the modem or the modem is busy....sorry I am at work and not able to get the exact wording at this time). And of course that error message is not in the help files or on the website. I have spent many hours at Sprint with no resolution only to be told it is my computer and not the card (which is probably true since it works on my work laptop). However I would hope someone at Sprint would have been able to help me figure out how to resolve this problem. I feel like I wasted my money since I purchased it to use at home and am now stuck in a 2 year contract. Has anyone else had a problem like this????
Any help would be greatly appreciated!!!