"Orders placed the week of April 7th are currently being shipped," Psystar said in a note posted on its site.
An alert on the site Friday said the store was "temporarily down." Psystar blamed the closure on the failure of its credit processing system, and not legal pressure from Apple.
Psystar now says it can again take orders again "thanks to our new high volume payment processor."
Last week, Psystar introduced a system called OpenPro. It's a beefed-up version of its Open Computer clone. The company claims it will ship either with a choice of preinstalled operating systems that includes Ubuntu Linux 8.04, Windows Vista, Windows XP, or Apple's Mac OS X 10.5 "Leopard."
Ubuntu is free. Vista or XP costs an extra $150, while Leopard costs an additional $155, according to Psystar's Web site.
Psystar says its Mac clones cost about one-quarter of what Apple-branded systems go for. The company charges that Apple marks up the cost of the hardware on which its operating systems ride by as much as 80%.
One version of Psystar's Open Computer features Apple's Leopard operating system ported onto generic PC hardware that includes an Intel Core 2 Duo processor at 2.66 GHz, a 250-GB hard drive, and an Nvidia GeForce 8600 GT graphics card.
The system is priced at $804.99. A similar Apple-branded computer would cost more than $2,000.
The problem: Apple's end user license agreement expressly forbids installation or sales of its operating systems on third-party hardware.
Psystar changed the name of its Mac clone from OpenMac to Open Computer last week -- perhaps in response to anticipated legal pressure from Apple. "The name 'Open' has been selected to reflect the fact that ANY consumer operating system can be installed and run on it," said Psystar.