I reported this on early Vanilla. Seemed to go away (or at least reduce, or I just got used to it) with later Vanilla/Warlords but is back with a vengeance on BTS. Seems to happen randomly - several times a turn on long turns - and you now absolutely need tooltips, e.g. to handle the random events.
I suspect that there are several variants of the same problem with different severity (some sort of context nesting problem).
It is easy to reproduce a less severe case on my machine - just select a unit using the right click menu - then enter the technology advisor. There will not be any tooltips showing the number of beakers required (Saved game attached from BTS 3.02 with hof mod). In this case tooltips comes back very quickly (e.g exit the advisor and double click an empty tile) but on other occasions the effects are more severe.
Other info that might be related:
Can sometimes get tooltips back by double clicking an empty tile.
Can sometimes get tooltips back by double-clicking on a foreign city (but not my own).
Also - sometimes - the tile information display at the bottom left of the main screen area gets stuck showing information about the tile occupied by the last unit accessed.
Sometimes when I alt-tab out the mouse is continually dragged to the top left hand corner of the screen until I alt-tab back.
Dell Inspiron 9300 2GB Ram (Latest Dell BIOS A05)
ATI MOBILITY RADEON X300 128MB (With latest dell drivers) 1920x1200
Using external Logitech Click! optical mouse
=====================================
OS Name Microsoft Windows XP Home Edition
Version 5.1.2600 Service Pack 2 Build 2600
OS Manufacturer Microsoft Corporation
System Manufacturer Dell Inc.
System Model Inspiron 9300
System Type X86-based PC
Processor x86 Family 6 Model 13 Stepping 8 GenuineIntel ~1729 Mhz
BIOS Version/Date Dell Inc. A05, 19/09/2005
SMBIOS Version 2.3
Windows Directory C:\WINDOWS
System Directory C:\WINDOWS\system32
Boot Device \Device\HarddiskVolume2
Locale United Kingdom
Hardware Abstraction Layer Version = "5.1.2600.2180 (xpsp_sp2_rtm.040803-2158)"
Time Zone GMT Daylight Time
Total Physical Memory 2,048.00 MB
Available Physical Memory 1.33 GB
Total Virtual Memory 2.00 GB
Available Virtual Memory 1.96 GB
Page File Space 2.60 GB
Page File C:\pagefile.sys
Name ATI MOBILITY RADEON X300
PNP Device ID PCI\VEN_1002&DEV_5460&SUBSYS_20021028&REV_00\4&27EA4097&0&0008
Adapter Type ATI MOBILITY RADEON X300 (0x5460), ATI Technologies Inc. compatible
Adapter Description ATI MOBILITY RADEON X300
Adapter RAM 128.00 MB (134,217,728 bytes)
Installed Drivers ati2dvag.dll
Driver Version 6.14.10.6561
INF File oem60.inf (BR_25822_ati2mtag_M22 section)
Color Planes 1
Color Table Entries 4294967296
Resolution 1920 x 1200 x 60 hertz
Bits/Pixel 32
Memory Address 0xD0000000-0xD7FFFFFF
I/O Port 0x0000DE00-0x0000DEFF
Memory Address 0xDFDF0000-0xDFDFFFFF
IRQ Channel IRQ 16
I/O Port 0x000003B0-0x000003BB
I/O Port 0x000003C0-0x000003DF
Memory Address 0xA0000-0xBFFFF
Driver c:\windows\system32\drivers\ati2mtag.sys (6.14.10.6561, 1.21 MB (1,273,344 bytes), 29/07/2005 00:54)
Hardware Type HID-compliant mouse
Number of Buttons 5
Status OK
PNP Device ID HID\VID_0D3D&PID_0001&MI_01&COL01\9&3AC86194&0&0000
Power Management Supported No
Double Click Threshold 6
Handedness Right Handed Operation
Driver c:\windows\system32\drivers\mouhid.sys (5.1.2600.0 (XPClient.010817-1148), 11.88 KB (12,160 bytes), 05/08/2005 22:20)
Hardware Type PS/2 Compatible Mouse
Number of Buttons 5
Status OK
PNP Device ID ACPI\PNP0F13\4&15F2F7D1&0
Power Management Supported No
Double Click Threshold 6
Handedness Right Handed Operation
IRQ Channel IRQ 12
Driver c:\windows\system32\drivers\i8042prt.sys (5.1.2600.2180 (xpsp_sp2_rtm.040803-2158), 51.50 KB (52,736 bytes), 03/08/2004 23:14)