Thank you very much Andrew, it looks like the problem was the useprobes option (I inhereted the script from another designer and, although I didn't need it, I thought that the useprobes option was harmless for my simulations...looks like I was wrong...again...:) ).
By the way, I have another problem. The circuit I am simulating is quite big, and if I use the save=all or save=allpub a file of 50GB is generated as the output of a tran analysis. If I select just a few signals of interest to be saved and use save=selected option the file is much smaller, but still measured in GB (about 7 - 8). The problem is that when I try to view the results with wavescan or ocean, sometimes, the application can not handle such big files. Do you know a way to overcame this problem?...maybe there is a way to separate the saved signals in several files instead of just only one...