I think I remember hearing that the word "password" is a reserved word in Access, so you have to enclose the word "password" in braces in your SQL statement:
For Example:
strSQL = "INSERT INTO tblUSER Username,[Password] VALUES('" & Request.Form("txtuser") & "','" & Request.Form("txtpassword") & "')
Hope this solves your problem.. I once made this mistake and it cost me a day of work.