Hi,
right click on My Computer and click on Manage. Here select "Shared Folders"
and then select "Sessions". How many sessions do you see? 5 or 10? If there
are 10 then you reached Windows XP limit and it can't be changed. If there
is 5 then click here on Shares and select your share. Open properties of the
Share and Check that under User limit it is set "Maximum Allowed" and not
any other setting.
I hope this helps you out,
Mike