What steps will reproduce the problem?
1. Upgrade to 5.20
2. Login

What is the expected output? What do you see instead?
Upon upgrading to version 5.20, a number of errors are produced. Most are fixed by simply deleting Shockandawe's saved variables but not all.

What version of the product are you using?
5.20

Do you have an error log of what happened?
Swatter gives this error when active:
Date: 2009-11-30 04:37:03
ID: 1
Error occured in: Global
Count: 1
Message: AceLocale-3.0: ShockAndAwe: Missing entry for 'Stormstrike if no Debuff'
Debug:
   (tail call): ?
   ...e\AddOns\Armory\Libs\AceLocale-3.0\AceLocale-3.0.lua:23
      ...e\AddOns\Armory\Libs\AceLocale-3.0\AceLocale-3.0.lua:21
   ShockAndAwe\Priority.lua:146 in main chunk
AddOns:
  Swatter, v3.1.14 (<%codename%>)
  ACP, v3.2.0.23
  Armory, vv7.4.3
  ArmoryGuildBank, vv7.4.3
  Auctionator, v2.5.2
  Babylonian, v5.1.DEV.130
  Configator, v5.1.DEV.190
  DoTimer, v4.3.6
  Gatherer, v3.1.14
  Livestock, v1.2.1
  Omen, v3.0.8
  QuestHelper, v1.2.7
  ReagentHelper2, vv2.0.9
  Recount, v
  ShockAndAwe, v5.20
  BlizRuntimeLib_enUS v3.2.2.30200 <us>
  (ck=170)

Blizzard's base UI gives this error:
Message: Interface\AddOns\ShockAndAwe\ShockAndAwe.lua:662 attempt to call method 'CreatePriorityFrame' (a nil value)
Time: 11/30/09 04:46:19
Count: 1
Stack: [string "Interface\FrameXML\BasicControls.xml:<Scrip..."]:18: in function <[string "Interface\FrameXML\BasicControls.xml:<Scrip..."]:4>
(tail call): ?
Interface\AddOns\ShockAndAwe\ShockAndAwe.lua:662 in function <Interface\AddOns\ShockAndAwe\ShockAndAwe.lua:645
(tail call): ?
[C]: ?
[string "safecall Dispatcher[1]"]:9: in function <[string "safecall Dispatcher[1]"]:5>
(tail call): ?
...ddOns\ShockAndAwe\Libs\AceAddon-3.0\AceAddon-3.0.lua:513 in function `InitializeAddon'
...ddOns\ShockAndAwe\Libs\AceAddon-3.0\AceAddon-3.0.lua:625 in function <...ddOns\ShockAndAwe\Libs\AceAddon-3.0\AceAddon-3.0.lua:618
[C]: in function `LoadAddOn'
[string "Interface\FrameXML\BasicControls.xml:<Scrip..."]:7: in function <[string "Interface\FrameXML\BasicControls.xml:<Scrip..."]:4>
...Ons\ShockAndAwe\Libs\AceLocale-3.0\AceLocale-3.0.lua:34 in function <...Ons\ShockAndAwe\Libs\AceLocale-3.0\AceLocale-3.0.lua:32
Interface\AddOns\ShockAndAwe\Priority.lua:146 in main chunk

Locals: self = <table> {
 defaults = <table> {
 }
 GetMSalpha = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:1897
 showUptimeQuery = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:1817
 getWindfuryColour = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:2356
 TidyUpAfterCombat = <function> defined @Interface\AddOns\ShockAndAwe\ShockAndAwe.lua:1049
 CancelTimer = <function> defined @Interface\AddOns\ShockAndAwe\Libs\AceTimer-3.0\AceTimer-3.0.lua:312
 ActivatePriority = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:2629
 getFlameShockDotColour = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:2290
 SetSixteenthPriority = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:2621
 WFProcBar = <function> defined @Interface\AddOns\ShockAndAwe\ShockAndAwe.lua:1587
 ActivateShear = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:1413
 SetCooldownThreshold = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:2116
 mw4soundplayQuery = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:1837
 setWindfuryColour = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:2361
 ScheduleTimer = <function> defined @Interface\AddOns\ShockAndAwe\Libs\AceTimer-3.0\AceTimer-3.0.lua:277
 GetSixteenthPriority = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:2617
 SetFifthPriority = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:2533
 GetMsgFont = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:1873
 CreateMsgFrame = <function> defined @Interface\AddOns\ShockAndAwe\ShockAndAwe.lua:2040
 SetMsgFont = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:1993
 db = <table> {
 }
 mw5flashQuery = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:1841
 SetEnabledState = <function> defined @Interface\AddOns\ShockAndAwe\Libs\AceAddon-3.0\AceAddon-3.0.lua:441
 SetWSMana = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:2141
 GetFifthPriority = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:2529
 ActivateFSDotBar = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:1403
 EnablePetFrame = <function> defined @Interface\AddOns\ShockAndAwe\ShockAndAwe.lua:1263
 setFrostShockColour = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:2309
 CreateStatsFrame = <function> defined @Interface\AddOns\ShockAndAwe\Stats.lua:52
 setLavaBurstColour = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:2428
 UnregisterAllEvents = <function> defined @Interface\AddOns\ShockAndAwe\Libs\CallbackHandler-1.0\CallbackHandler-1.0.lua:201
 msgFrame = ShockAndAweMsg {
 }
 GetMaelstromInfo = <function> defined @Interface\AddOns\ShockAndAwe\ShockAndAwe.lua:1233
 GetShieldOrbs = <function> defined @Interface\AddOns\ShockAndAwe\Options.lua:1949
 purgeWar

Please provide any additional information below.
I've tested this with and without other addons running, same result.