Sent passwords only work sometimes

[Guest]

Hi,

I am having a problem with the passwords to my oscommerce site. When accounts are created or if passwords are resent, sometimes that password doesn't work. The site has been running without a hitch for about a yeah then all of a sudden this happens? I haven't changed any code during this period only added customers and products. If i need to send you any code samples please let me know.

Thanks,

Sam