Users of the affected models should either use an external reader or lower capacity cards Three models of Memory Stick Pro memory card recently launched by Sony and one to be launched on Friday won’t work with some of the company’s Vaio desktop computers plus 13 of the company’s Clié PDAs (personal digital assistants), Sony said Wednesday.The announcement is the second admission within a week from the company that a new version of one of its products isn’t completely backwards compatible. Late last week, Sony Computer Entertainment, the Sony division responsible for the PlayStation game console, said that a new version of the PlayStation 2 due on sale in Japan on Nov. 23 had problems running almost 50 existing software titles.The card problem concerns the MSX-M1GST, 1GB Memory Stick Pro Duo card; the MSX-2GS, a 2GB Memory Stick Pro card; the MSX-M2GS, a 2GB Memory Stick Pro Duo card; and the PSP-MP1G, a 1GB Memory Stick Pro Duo card, Sony said in a statement. The latter card is scheduled to go on sale in Japan on Friday branded for use with the PlayStation Portable while the two 2GB cards went on sale on Sept. 9. The cards won’t work with the internal Memory Stick readers in several models of Vaio computer and users should either use an external reader or lower capacity cards, the company said. The affected computers are the Vaio type V, models VGC-V202RB, V202, V201, V172B, V172EB, V172S, V171B and V171; Vaio type M, models VGC-M50B/S, M30B/W, M30/W and M70/W; and Vaio P, model PCV-P101. The problem also affects some models sold in Europe.They also won’t work with 13 models of Clié PDA: the PEG-VZ90, UX50, NX80V, NX73V, NZ90, NX70V, NX60, TH55, TH55DK, TJ37, TJ25, TG50 and the PEGA-VR100K. All of the PDAs are based on version 5 of the Palm operating system.The compatibility problems stem from changes in the internal components used inside of the cards, said Daichi Yamafuji, a Sony spokesman in Tokyo. Sony launched Memory Stick Pro at the Consumer Electronics Show in Las Vegas, U.S., in January 2003. At the time the company said the format specified versions of the card up to 32GB and also said a 2GB card was being developed.The computers that have problems reading the cards were on sale in Japan at various times between late 2003 and late 2004. Technology IndustrySmall and Medium Business