VM and Procmail

Hi,
 Recently I started using procmail to sort my incoming  mail into  VM
folders [Xemacs version no is 19.14] and I noticed that if I get a new
mail while  I am visiting a folder the folder gets confused i.e when I try
to quit the folder a message pops up with a question "The folder has
changed since the last visit Save ? "and if I select Yes it overwrites the
folder resulting in lost mail.Can someone help me solve this problem?.

thanks,
deena