A Fork is the same as a collision? How many technical problems do you know about, and which one is the most dangerous ( with Bitcoin) ?
What do you mean with collision? Key collision?
If so, no, a fork is entirely different, and the two are barely (if not) related.
Also, i'd say that a key collision isn't really a problem. Although it is possible, it is extremely unlikely to happen on the regular. See
https://bitcoin.stackexchange.com/questions/7724/what-happens-if-your-bitcoin-client-generates-an-address-identical-to-another-peAlso, ( soft/hard) forks aren't a "danger" for bitcoin per se. More often than not they're done to improve the state of the bitcoin network. (SW)