Not sure if you have an answer yet but I would check my data layout for synthetic keys. Try to reload the model useing the limited load in the debug option. Keep it at 10 rows per table. This will hopefully complete the load successfully.
You can then view your data layout and see if there is a problem with it. You will most probably find a big synthetic key that is causing your problem.
The reason it fails is both of your table have some fields which have same name.
Now let me explain what happens in background.
by default Qlikview does the joining of tables on the basis of common name. for example
Say you have Table 1 with fields ABC,PQR,XYZ and Table 2 with fields ABC,KLM,WER
Then in this case both the table will be linked with the ABC field.
In case if you have more than 1 same field in table, qlikview tries to join them and creates a synthetic keys. Thus it takes longer time for creating synthatic keys.
So in your case make sure that you give identical names to the fields, and in case you want to link the table use the single primary key to link them.
Hope its clear to you now.