Out of general interest I wrote a small program that will reveal all the cards in any deal in the 1998 Microsoft Windows version of Spider. Every game starts with a 31-bit "seed" generated at random, and the cards are dealt progressively using a fixed algorithm based on that seed. Every game can be reproduced if you know its seed, and the only way a game could be "fixed" would be if the program had a huge list of "difficult" seeds and was coded to select one in certain circumstances. In the thousands of games I've played there has been no suggestion of this, and I have not found any evidence of this when looking through the Microsoft program code. I'm certain that the game is not fixed in any way.
Because my program can also generate the full deal for any possible seed and create a "saved" file for it, I can test and play any of the 2.1 billion possible games that the 1998 Microsoft Spider program can generate.
I have also run all of the possible games through my program to search for an "impossible" game - where the exposed row of 10 cards and every one of the 5 rows of 10 undealt cards has no possible moves. Out of the 2.1 billion possible 4-suit games there are just 44 where 4 of the 6 rows have no possible moves (but none with more than 4). 11 of the 44 have one or more cards that match with the row above (e.g. 5 of clubs on top of the 6 of clubs in the same column of the previous row) and a subsequent move is now available. I am fairly confident that amongst these 44 games there must be at least one that is impossible!
The later version of Microsoft's Spider available in Windows 10 uses a different algorithm to generate the dealt cards and I have not been able to deconstruct it, so I can't offer any information here. The 1998 version works fine in Windows 10 and is the one I still use.