[AT&T, Rogers HTC One X, Telstra One XL] anield:
Ok I will tks. I'm trying to do RUU 3.18.502.6 same as OP. Rooted, S-OFF & supercid on 1.85 last year. Have been running CleanROM 4.5 & decided it was time to move to JB and CleanROM 6.5.

Here's some snips from RUU log (don't think I have enough posts to attach it):

<CMD>fastboot -s HT25TW303924 getvar version-main</CMD>
<OUT>version-main: 1.85.502.3</OUT>
...
<T231856><DEBUG><CMD>fastboot -s HT25TW303924 erase cache</CMD>
</DEBUG></T231856>
<T231857><DEBUG><OUT>erasing 'cache'... OKAY</OUT>
</DEBUG></T231857>
<T231857><DEBUG>Try to read image count from android-info.txt in C:\Users\user\AppData\Local\Temp\{973781A8-65F1-4556-94C5-E1795C3B693E}\{50F2F878-636A-496F-A7CB-544C067E0C4B}\rom_01.zip
</DEBUG></T231857>
<T231857><DEBUG><CMD>fastboot -s HT25TW303924 flash zip C:\Users\user\AppData\Local\Temp\{973781A8-65F1-4556-94C5-E1795C3B693E}\{50F2F878-636A-496F-A7CB-544C067E0C4B}\rom_01.zip</CMD>
</DEBUG></T231857>
<T231859><DEBUG><OUT>sending 'zip' (386 KB)... OKAY</OUT>
</DEBUG></T231859>
<T231859><DEBUG><OUT>writing 'zip'... INFOadopting the signature contained in this image...</OUT>
</DEBUG></T231859>
<T231859><DEBUG><OUT>FAILED (remote: 92 supercid! please flush image again immediately)</OUT>
</DEBUG></T231859>
<T231859><DEBUG><OUT />
</DEBUG></T231859>
<T231859><DEBUG>32bit HSM, strPath = C:\Program Files (x86)\HTC\HTC Sync 3.0\HTC Sync\
</DEBUG></T231859>
<T231859><DEBUG><CMD>adb devices</CMD>
</DEBUG></T231859>
<T231859><DEBUG><OUT />
</DEBUG></T231859>
<T231859><DEBUG><CMD>fastboot devices</CMD>
</DEBUG></T231859>
<T231901><DEBUG><OUT>????????????	fastboot</OUT>
</DEBUG></T231901>
...
<T231909><DEBUG><CMD>fastboot -s HT25TW303924 getvar boot-mode</CMD>
</DEBUG></T231909>
<T231912><DEBUG><OUT>boot-mode: RUU</OUT>
</DEBUG></T231912>
<T231912><DEBUG><CMD>fastboot -s HT25TW303924 flash zip C:\Users\user\AppData\Local\Temp\{973781A8-65F1-4556-94C5-E1795C3B693E}\{50F2F878-636A-496F-A7CB-544C067E0C4B}\rom_01.zip</CMD>
</DEBUG></T231912>
<T231912><DEBUG><OUT>sending 'zip' (386 KB)... OKAY</OUT>
</DEBUG></T231912>
<T231912><DEBUG><OUT>writing 'zip'... INFOadopting the signature contained in this image...</OUT>
</DEBUG></T231912>
<T231912><DEBUG><OUT>INFOzip header checking...</OUT>
</DEBUG></T231912>
<T231912><DEBUG><OUT>INFOzip info parsing...</OUT>
</DEBUG></T231912>
<T231912><DEBUG><OUT>FAILED (remote: 99 unknown fail)</OUT>
</DEBUG></T231912>
<T231912><DEBUG><OUT />
</DEBUG></T231912>
<T231912><DEBUG>32bit HSM, strPath = C:\Program Files (x86)\HTC\HTC Sync 3.0\HTC Sync\
</DEBUG></T231912>
<T231912><DEBUG><CMD>fastboot -s HT25TW303924 oem rebootRUU</CMD>
</DEBUG></T231912>
<T231914><DEBUG><OUT>... INFOStart Verify: 3OKAY</OUT>
</DEBUG></T231914>
...
<T231923><DEBUG><CMD>fastboot -s HT25TW303924 getvar boot-mode</CMD>
</DEBUG></T231923>
<T231924><DEBUG><OUT>boot-mode: RUU</OUT>
</DEBUG></T231924>
<T231924><DEBUG>Try to read image count from android-info.txt in C:\Users\user\AppData\Local\Temp\{973781A8-65F1-4556-94C5-E1795C3B693E}\{50F2F878-636A-496F-A7CB-544C067E0C4B}\rom_02.zip
</DEBUG></T231924>
<T231925><DEBUG>The rom is encrypted, read the header instead.
</DEBUG></T231925>
<T231925><DEBUG>signed rom
</DEBUG></T231925>
<T231925><DEBUG>getImageCount, nHR: 23
</DEBUG></T231925>
<T231925><DEBUG><CMD>fastboot -s HT25TW303924 flash zip C:\Users\user\AppData\Local\Temp\{973781A8-65F1-4556-94C5-E1795C3B693E}\{50F2F878-636A-496F-A7CB-544C067E0C4B}\rom_02.zip</CMD>
</DEBUG></T231925>
<T232009><DEBUG><OUT>sending 'zip' (645386 KB)... OKAY</OUT>
</DEBUG></T232009>
<T232009><DEBUG><OUT>writing 'zip'... INFOzip header checking...</OUT>
</DEBUG></T232009>
<T232009><DEBUG><OUT>FAILED (remote: 32 header error)</OUT>
</DEBUG></T232009>