Lemurian,
In my incident we were in cirrus cloud with ice flowing up the windscreen (SAT -50C note!) when all speed indications to the left PFD were lost (Vmax and VLS came together) and right PFD speed dropped to an inaccurate 160kts. A/P and ATH disconnected. The ECAM was almost unreadable due to it constantly streaming and changing. Alternating `STALL, STALL` and high speed warnings received. What was initially the most pressing problem was to maintain the speed down to the ALT2 MMO of .82M versus normal MMO.
Once out of icing after a priority descent the probes cleared and the flight continued for ~1.5 hrs to destination - still in ALT2 law. This happened 14 years ago and resulted in several changes to the hardware and software of the A330.