Drupal Multi-step form breaks with node save

I have a custom multi-step form that I add to certain node type content via hook_nodeapi. It is working great, with one exception.

During testing, I've found that when I am in mid-form (say, step 2 of 6) and update the node in another browser tab, my form reverts to step 1 when I try to proceed to the next step. Similarly, when an AHAH event occurs, I get an error and the form disappears altogether. The error suggests there is a problem with retrieving the form from cache after a node update, as it's not able to retrieve the form parameters.

Have you encountered this behaviour before, and/or do you have any suggestions on how I might go about fixing it? It isn't a huge problem as these nodes likely won't be updated too often on the production side, but it would still be a significant 开发者_开发问答nuisance to those it does affect.

Edit: Thanks for your response. Unfortunately I can't contain this form within a block. It must be within the node content itself. Upon further testing I noted that other users thankfully aren't affected. It is only the user that updates the node while in mid-form that is affected. As this is extremely unlikely to happen on the production site, the impact of such an occurrence would be minor, and I have no time at the moment to explore this further, I'm going to move on with this behaviour unexplained for now. But if anyone can point out why this is occurring, I'd appreciate it.

Well, have just tried your situation based on multistep form described here - http://zgadzaj.com/basic-drupal-multipart-form-example-with-previous-and-next-buttons - but put in the block and displayed on node page, and even if I edit this node in a different tab, I still can navigate between all form steps on the original tab, keeping all already submitted values. So I'd say it all probably depends how your form is being built...