There are no "withdrawal problems" on Bitstamp. Not fiat, not Bitcoin. Not a single documented case. Head over to the services subforum and find the relevant thread and check for yourself.
There are rather intrusive questions asked when you withdraw larger sums, either fiat or Bitcoin. After those questions are answered, the withdrawals go through immediately. Anyone disagreeing on this, please, by all means, report in.
So let's keep things separate: Withdrawal problems are one thing. At the first sign, I'd like to know about them. The other thing is an exchange that tries to cover its ass when the inevitable subpoenas come in related to money laundering, Silk Road, etc. Bitstamp is rather nosy in that respect, but I prefer that to be honest over them being closed down if they can't answer to those subpoenas properly.
That's the deal: you want anonymity? Mine, or buy on btc-e. You want liquidity, and low counterparty risk? Bitstamp.
I guess that falls under what you define a problem as.
Can't withdraw fiat even though you're verified without asking intrusive questions above and beyond what a company could possibly need to know for KYC/AML, add on the fact that many people can't sign their most used deposit address then I'd call it a problem.
Insolvency is a different question but when you want your money that they were happy for you to deposit in the first place without asking where it came from then, to me, thats a pretty big problem.
No, see, you're lawyering now. Not even that, you're twisting words.
We all know what "withdrawal problems" mean in the context of Bitcoin exchanges: the inability to serve withdrawal requests of customers.
And that's exactly what is not going on over at Bitstamp. What is going on is that, at some point during the past year, (a) they decided they want to establish a more intrusive KYC procedure for large withdrawals, and (b) that they don't want to make a big public announcement about it.
I support their right to do (a), but would have preferred if they would have avoided doing it rather backhandedly, i.e. I don't support (b). But by now everyone who follows the Bitstamp thread knows about it, so it's, if you want to call it, an open secret: if you want to deal in large(ish) sums on Bitstamp, prepare for the additional KYC questionnaire.