Regarding the previously reported problem with blinking ? on warm restarts (and sometimes even on cold starts) with PowerBase clones, Power Computing reports:
In the majority of cases, if the computer is powered off and restarted, the computer will boot properly. More importantly: Power Computing has identified an issue with a limited number of IDE (ATA) 1.2 GB hard disk drives used with PowerBase computers. This issue can occur with Mac OS 8 or a previous versions of the Mac OS. Power Computing uses the Apple IDE driver installed by the Mac OS Drive Setup utility. Drivers installed by versions of Drive Setup 1.2 or later been known to expose this issue. Customers should either contact Power Computing Technical Support or their reseller for further assistance with this issue."
This seems very similar to the issue reported for these drives on several Apple Mac models.
Meanwhile, James Baumhover says that he has seen postings from Apple that disabling the sleep function for the hard drive has helped solve this problem. I cannot confirm this.