That said, and much like the OP's predicament, there are countless, endless users putting Nuendo to it paces without so much as a hint of a problem. There is no inherent flaw that makes Nuendo an inferior input recording device. Nuendo like Pro Tools, at it's fundamental core, is rock solid. It didn't work for you and I get the frustrating component of that. You wouldn't be the first I've encountered that just couldn't (for whatever reason) get to the bottom of their own personal PC woes an an accompanying piece of software. But because it didn't work for you doesn't mean the software (properly configured) isn't light years more capable and elementarily as solid as any stand alone device. Simply put, it is.
Spend enough time recording and you'll see everything crash and burn at some point... I've had both Macs & Windows machines go down or just cough and spit up a project with the same amount of frequency. Computers, DAW software and all that really makes no difference. Nothing is immune from failure or ill-configuration.
The absolute best way to screw up any DAW is to multi-task the computer. Doesn't matter if its Sonar, Monkey Toolz, Nuendo etc they all want to live and will give you the absolute best performance on a dedicated machine. Settings for general computing & websurfing don't translate to great DAW performance... sure every program has its own quirks but they all demand certain things from the OS and things like wireless networks are gonna screw with your interface and create all kinds of havoc, like crazy latency and dropouts while recording.
This is all assuming of course that you've got legit software. Maybe because I've done a lotta PC support over the years it seems like whenever someone has a problem with "Nuendo" it turns out they're running some cracked copy "a friend gave 'em" on a virus laden machine. Could say I wish I had a nickle for each time that happened but ehhh... I do!!! Lets be honest, how many people are gonna drop $2k on software when they have a $150 interface and a couple SM57?