Beginning late last week, some Apple users noticed that the Windows version of iTunes would abruptly quit just as they were in the process of purchasing music from the online store.
By Monday, more than three dozen users were complaining about the problem in Apple's online forum. An Apple representative declined to comment.
In an e-mail interview, iTunes customer Sherman Hall said he experienced the glitch on Thursday.
"The program stopped with a memory exception after downloading two songs," Hall said. "Attempts to restart the download, access my account information or any other one-click activity were also met with the same memory error."
Some in the discussion forum said the problems followed shortly after they installed an update to Windows XP Service Pack 2. Hall said his computer installed the Windows update on Wednesday evening.
A Microsoft representative declined to comment on the issue.
Apple hasfrom its site, and the store has had few hiccups amid its rapid growth. The company has continued to dominate the category despite growing competition from rivals such as Sony, Napster and Wal-Mart.