Deactivated - Customer Accounts

Hi guys, we've been experiencing an odd problem for the last few weeks. Joomla User Accounts will randomly switch from "Enabled" and "Activated" to "Enabled" and De-Activated". Nothing shows under Hikashop customer accounts, but we've had many customers call in because they're unable to login or reset their passwords and when we go over the the Joomla User Account section it's "Enabled" & "De-Activated. So, basically I just click the little "Activate" icon next to their name and they're good to go. I've been periodically going through the accounts to check for this issue and I can't figure out what's causing this. I can't pin point a specific action that is similar or common between any of these accounts. They range from customers who order every few days, every few weeks and once a month. Nothing in their orders, order dates, account types, etc. are similar, yet I just found 4 more. All 4 of these customers had 2 or more orders already in the system before the account randomly "De-Activated". Has anyone else experienced this issue or has any suggestions? Thanks guys.

Hugs,

Natalie