Sony has denied that its PlayStation network has been hacked after some people in the UK reported problems.
Users have been tweeting PlayStation`s support account for several days saying that their accounts have been frozen and they are unable to log in.
Some also said that they appeared to be missing funds.
In a statement, Sony told the BBC the network had not been compromised and advised people to make sure they had robust security measures in place.
"We routinely monitor for irregular activity, and if such activity is detected, we may sometimes reset passwords of affected accounts to protect users and their account information," Sony said.
"We strongly advise users to keep a close eye on their accounts for unusual activity and avoid entering your username/password into unofficial sites looking to phish credentials based on fake promotions."
On Twitter, the firm has apologised for the delay in reinstating accounts and says that the company helpline is "particularly busy at the moment".
Cybersecurity expert Professor Alan Woodward said if there had been a breach, the leaked data would probably have appeared elsewhere.
"There are two ways this could happen: either someone has got into Sony`s central systems, which have been compromised before, or people`s individual systems have been compromised," he told the BBC.
`If there had been some kind of central breach, the dark web would have been alight with it and we in the industry would be aware of it by now, I have not seen anything.
"If individual accounts had been breached and Sony had reset their passwords then users would expect to be notified by email.
"The fact they haven`t suggests that usernames and passwords have been given away unintentionally," he added.
"Clearly if someone is spending money it is criminal activity."
Sony was unable to clarify how many users were affected and the issue only appears to be affecting PlayStation users in the UK.